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<div class="moz-cite-prefix"><br>
Why does a URN have to be registered?<br>
<br>
If one of our documents says <urn:step:inch><u> in a STEP
model</u> means an inch as defined at <span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"></span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif""><a
moz-do-not-send="true"
href="http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH"><http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH></a></span>;
is anybody going to complain, and if so to whom?<br>
<br>
Martin<br>
<br>
On 6/11/2014 1:26 PM, Barkmeyer, Edward J wrote:<br>
</div>
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Fine.
Then someone has to do the ICANN registration process for
urn:step! And since I assisted Joanna Goodwin and Holger
Apel with that rigamarole producing RFC 5141, I can tell you
they didn’t make it easy. It is NOT like paying $100 for a
domain name.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
undertook that for SC4, so that
urn:iso:std:iso:10303:term:xxx would be automatically valid,
and so that SC4 could define URNs beginning
urn:iso:std:iso:10303:tech and other such identifiers. If
you want urn:step, you should have stepped up in 2004-5 when
we did that (but you probably would not have had support
from JTC1 and TC68 and TC154).<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
don’t really care whether you use URNs or not. Sir Tim got
his way and denatured http: and made the whole URN effort
largely useless. (It was neither the first nor last waste
of my time in standards land.) What you do have to realize
is that there is a formal procedure for creating URIs of
either kind, and if you elect not to use what has already
been done, you get to put the resources into repeating the
procedure.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">STEP
as a whole is a sow’s ear, but it works and using it is a
lot cheaper than trying to roll your own silk purse.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Ed<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in
0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"
style="text-autospace:ideograph-numeric ideograph-other"><b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">
Martin Hardwick [<a class="moz-txt-link-freetext" href="mailto:hardwick@steptools.com">mailto:hardwick@steptools.com</a>]
<br>
<b>Sent:</b> Wednesday, June 11, 2014 12:56 PM<br>
<b>To:</b> Barkmeyer, Edward J; Thomas.r.thurman<br>
<b>Cc:</b> Thomas Liebich; wg11; Palmer, Mark E. Mr.;
<a class="moz-txt-link-abbreviated" href="mailto:magne.valen.sendstad@gmail.com">magne.valen.sendstad@gmail.com</a><br>
<b>Subject:</b> Re: [wg11] units of measure, from
Minutes of Part 21 E3 DIS testing telecon on June 5,
2914<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On 6/11/2014 12:39 PM, Barkmeyer,
Edward J wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Martin,</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Why
is:
</span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif""><a
moz-do-not-send="true"
href="http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH"><http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH></a></span>;<o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif"">less
“convoluted” than:</span>
<span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
urn:iso:std:iso:31:term:metre</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">???</span><o:p></o:p></p>
</blockquote>
<p class="MsoNormal" style="text-autospace:ideograph-numeric
ideograph-other"><span style="font-size:12.0pt">You tell me.
I want to use <urn:step:inch><br>
<br>
As implementors we have found that less typing means less
scope for mistakes. <br>
<br>
If there is going to have to be lots of typing then </span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif""><a
moz-do-not-send="true"
href="http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH"><http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH></a></span><span
style="font-size:12.0pt">; is better than </span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">urn:iso:std:iso:31:term:metre
</span><span style="font-size:12.0pt">because there are lots
of ways to check for badly type URL's and hardly any to
check a badly typed URN.<br>
<br>
Your URN requires me to remember:<br>
1. Type iso twice<br>
2. The standard number is 31<br>
3. The concept being defined is a term<br>
<br>
As an implementor I can do all this. Just look at what we
did for units in Part 21 Edition 1 and 2.
<br>
<br>
Martin<br>
<br>
<br>
</span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
http: form just uses a different ISO CS directive for
formulating IRIs, which is “jealously guarded” by ISO CS
in exactly the same way!</span><span
style="font-size:12.0pt">
<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">In
both cases, ISOCS specifies what everything up to the
“tech” part must be, and the SC gets to define what
follows.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
point of the ISO URNs of the form above is that MERELY by
having the term defined in an existing ISO standard, there
IS a standard IRI for the term. And if multiple standards
define “metre”, then it is very important that you know
WHICH meaning is intended by the reference!
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Why
would it be better for ISO 10303 to define what it means
by “inch” than what some industry reference standard
defines “inch” to mean? Do I have to find a different IRI
if I am using an ASTM standard? or an API standard? </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
problem is to get a reference standard that defines the
“conversion based units” (English measure, et al.) that we
want to be able to use, and then to use one of the
ISO-specified forms for creating the corresponding IRI,
whether it begins http: or urn:. Enabling such things is
exactly why ISOCS went to the trouble of registering the
URN and URL forms and publishing the corresponding
directives. And if the reference standard is not an ISO
standard, then we will be bound by whatever URI syntax
that particular SDO set up. So, if urn:ifc, or
<a moz-do-not-send="true" href="http://ifc.org/">http://ifc.org/</a>,
is an ICANN registered prefix, and the IFC defines
urn:ifc:inch, or whatever “convoluted” form IFC decides
on, we could use that and be done.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
point of all this is that the references for constructing
IRIs are already in place. What is necessary is the *<b>standard</b>*
that defines the terms you want to use, so that the IRI
that refers to that term in that standard can be
employed. Stop worrying about the IRIs and figure out
where/what the reference standard is to be. By way of
assisting in this, I have put in a request to a NIST
SI/BIPM person to identify an appropriate specification
for English measures, but I have not yet received a
response.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Ed</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<div style="border:none;border-left:solid blue
1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"
style="text-autospace:ideograph-other"><b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">
Martin Hardwick [<a moz-do-not-send="true"
href="mailto:hardwick@steptools.com">mailto:hardwick@steptools.com</a>]
<br>
<b>Sent:</b> Wednesday, June 11, 2014 6:35 AM<br>
<b>To:</b> Thomas.r.thurman<br>
<b>Cc:</b> Barkmeyer, Edward J; Thomas Liebich;
wg11; Palmer, Mark E. Mr.; <a
moz-do-not-send="true"
href="mailto:magne.valen.sendstad@gmail.com">
magne.valen.sendstad@gmail.com</a><br>
<b>Subject:</b> Re: [wg11] units of measure, from
Minutes of Part 21 E3 DIS testing telecon on June 5,
2914</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<p class="MsoNormal"><br>
Again my purpose is to investigate how P21 e3 might
help. The most we can venture is to produce some
recommendations and examples.<br>
<br>
My summary of the previous e-mails is that the ISO
namespace <urn:iso> is jealously guarded to keep
the peace between the committees. We are never going to
be able to use it to make something easy for the
implementors.<br>
<br>
However, before giving up on URN's I would like to get
opinion on the following: Can we define our own
namespaces?<br>
<br>
We might do this for each standard, or at the level of
SC4.<br>
<br>
For example, if we decide to use URNs to define units
for STEP then<br>
1. The URN for inch might be <urn:step:inch>;<br>
2. The URN would be mapped by appropriate wording in the
appropriate place to the URL
<br>
<a moz-do-not-send="true"
href="http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH"><http://standards.iso.org/iso/10303/tech/reference_data/-41/units.stp#INCH></a>;<br>
3. The URN would only have to have meaning for a STEP
model.<br>
<br>
We would then do the same for ifc <urn:ifc:inch>
and iso15926 <urn:iso15926:inch> etc.
<br>
<br>
The appropriate wording in #2 could be words in the
standards document, or it could be a rule in the
standards document telling you where to find a server
with the permitted URNs.
<br>
<br>
Martin Hardwick<br>
Team Leader ISO STEP-Manufacturing<br>
<br>
<br>
<br>
On 6/10/2014 8:15 PM, Thomas.r.thurman wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">The purpose behind the units thing
in P21 ed3 EXAMPLEs is to help move things forward,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">as opposed to just having examples
in p41.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">The BIPM has made general
quantities and units document publicly available, but
ISO 80000-x <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">is still behind a paywall which
means I have to buy a copy of it to understand what a
term means.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">What is the <b><i><u>business</u></i></b>
process for moving forward?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Regards,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Tom<br>
Sent from my iPad<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
On Jun 10, 2014, at 4:11 PM, Martin Hardwick <<a
moz-do-not-send="true"
href="mailto:hardwick@steptools.com">hardwick@steptools.com</a>>
wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"><br>
Hi Ed,<br>
<br>
Thanks for these comments and before anyone gets
the wrong idea let me state emphatically that Part
Edition 3 is NOT, NOT, NOT planning to define any
units. We are only looking at what might become
possible if URI's are allowed in the Part 21
standard.<br>
<br>
One option for the relevant committees is to keep
the status quo and demand that all units are
defined from first principles as is currently the
case in all the STEP Application Protocols. Thus
every time an inch is used it must be defined as
being 25.4 millimeters. (As an aside I wonder
what would happen if a file defined an inch as
25.3 millimeters. Would the software notice? Would
it follow through and convert all the units by the
given formula. Would the result be a correct
model? What about the accuracy constraints? Has
STEP been consistent about applying the conversion
across all the cases?)<br>
<br>
The second option is to use URL's. This is the
option that is being most actively investigated by
the P21 e3 group. This option is currently running
into several small issues with respect to
conversion based units. As I understand it the
issues are derived from problems in the PLIB
expression schema, but on a more personal level I
have always thought it crazy to encode expressions
in the PLIB expression schema.<br>
<br>
This started me thinking about the URN option in
more detail. As I understand it a URN is used when
the systems are expected to "know" the definition.<br>
<br>
Hence I wonder why we cannot define<br>
<br>
<urn:iso:inch><br>
<br>
In the context of an AP242 file this would mean
the current definition only with the conversion
GUARANTEED to be 25.4. For an OWL system it would
be whatever OWL systems expect and so on. It is a
URN so nothing has to be at the other end of the
definition, but something could be so STEP could
say this URN is defined by the definitions at the
following URL (which can then be as complex as any
standards organization can imagine).<br>
<br>
I really wonder what the advantage of a convoluted
URN such as <span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">urn:iso:std:iso:31:term:metre</span>
might be. Does this mean that different standards
groups are going to define different metres?<br>
<br>
There is also the practical issue for system
implementors of what to do if someone types the
URN's slightly wrong which increases as the URN
gets longer.
<br>
<br>
As an implementor <urn:iso:inch> seems just
about acceptable because there is very small
possibility that we will want to have two
definitions for inch in STEP files - one defined
by ISO and another defined by Martians
<urn:mars:inch>. A more practical example
might be the definition of pint which is different
between the UK <urn:iso:uk:pint> and the USA
<urn:iso:usa:pint>. I can see that ISO might
shy away from making this kind of distinction, but
in this case can STEP should define its own name
space <urn:step:inch> for its own STEP
files.<br>
<br>
Thanks for your attention. If we are going to have
to write URN's that are as long and convoluted as
the URL's then we may as well stick with the
URL's, so I am hoping there is a better solution.<br>
<br>
Martin<br>
<br>
<br>
<br>
On 6/10/2014 4:42 PM, Barkmeyer, Edward J wrote:<o:p></o:p></p>
</div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Martin,</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
agree that fuddling with Part 41 representations
of measurement units that should have reference
IRIs is “so 1990s”. But moving on requires a
wider commitment.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">urn:iso:
... is a well-defined identifier form, and ISO
CS is the registry for it. See IETF RFC 5141. (<a
moz-do-not-send="true"
href="http://www.rfc-editor.org/info/rfc5141">http://www.rfc-editor.org/info/rfc5141</a>)</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Some
of these units are defined terms in ISO 31, ISO
1000 and ISO 80000. As a consequence they have
a well-defined URN per the RFC.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">For
example, the URN for ‘metre’ is (I think):</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
urn:iso:std:iso:31:term:metre</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">It
is doubtless the case that one of the ISO
measurement units standards defines cm/s, but it
is unlikely that any defines ‘furlong’ or
‘inches per second’. That is why Part 41 has
the conversion_based_unit construct.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">SC4
has authority from ISOCS to define ISO URNs by
attaching :tech:<whatever> to any (Part of
any) SC4 developed standard identifier, with the
proviso that these identifiers are, in fact,
defined in the technical specification. It is
in fact possible for Part 21 to specify URNs of
the form:</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
urn:iso:std:iso:10303:tech: xxx</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">without
identifying the Part number. I suspect that
WG12 would consider it inappropriate for Part 21
to contain such specifications, however.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Further,
there is an issue in WG3 to align ISO 15926-4
with ISO 80000 and perhaps to incorporate some
elements of NASA QUDT, which is an OWL ontology
of every unit NASA has ever dreamed of using,
based on a fundamental ontology that mirrors ISO
80000 and the International Vocabulary for
Measures (VIM). So, it may be possible that
these desired “common units” have the form:</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
urn:iso:std:iso:15926:-4:tech:class:INCHES_PER_SECOND
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">or
something the like. It is definitely the intent
of WG3 that they will have a URI</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">
<a moz-do-not-send="true"
href="http://iso.org/std/iso/15926/-4">http://iso.org/std/iso/15926/-4#</a>
INCHES_PER_SECOND</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">or
something the like (and that is only because W3C
decided that http: is the universal prefix for
IRIs, and no longer denotes a protocol). But
WG3 would really prefer that QUDT was a
referenceable standard in its own right, with
its own IRI path.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">With
the above as background, it is important for SC4
to avoid participating in the construction of
another cottage industry. It would be a “good
thing” for SC4 to bring its interested parties
to a common table and come up with a common
solution to this problem for SC4 specifications,
instead of one-off conventions for the favorite
technology of each Working Group.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">-Ed</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<div style="border:none;border-left:solid blue
1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"
style="text-autospace:ideograph-other"><b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-family:"Tahoma","sans-serif";color:windowtext">
wg11 [<a moz-do-not-send="true"
href="mailto:wg11-bounces@steptools.com">mailto:wg11-bounces@steptools.com</a>]
<b>On Behalf Of </b>Martin Hardwick<br>
<b>Sent:</b> Tuesday, June 10, 2014 10:22
AM<br>
<b>To:</b> Thomas Liebich; wg11<br>
<b>Subject:</b> Re: [wg11] Minutes of Part
21 E3 DIS testing telecon on June 5, 2914</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<p class="MsoNormal">Hi Thomas,<br>
<br>
Thanks for this feedback.<br>
<br>
I am growing in favor of using a simple URN
for all the "famous" (well known units).<br>
<br>
Hence, we might have in the reference section
of a P21 e3 file:<br>
<br>
#10=<urn:iso:metre>;<br>
#20=<urn:iso:inch>;<br>
#30=<urn:iso:centigrade>;<br>
#40=<urn:iso:Fahrenheit>;<br>
#50=<urn:iso:furlong> ;<br>
#60=<urn:iso:inches-per-second>;<br>
<br>
And so on for all the units that the standards
want to recognize. There would not need to be
any files to define these units (but there
could be). Software systems would be expected
to "know" them from the URN and that would
include knowing how to convert between them. <br>
<br>
(Without benefit of a conversion based
expression - oh my gosh what will happen if
there is an apocalypse and the only people
left are idiot savant nerds who only know how
to follow mathematical expressions and cannot
remember any units except the ones stored in
the NIST library which was the only building
in Washington to survive the catastrophe of
course) - Yes I will be made to regret this
statement.<br>
<br>
Martin<br>
<br>
<br>
On 6/10/2014 9:29 AM, Thomas Liebich wrote:<o:p></o:p></p>
</div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"
style="margin-bottom:12.0pt">Dear all,<br>
<br>
only as a side remark. During our IFC
(ISO16739) developments we faced the same
issue - a derived unit involving factor and
offset cannot be defined with the current
conversion_based_unit.<br>
<br>
So we added a subtype to IFC4, which
essentially defines the same, as the proposed
extension here for P41.<br>
See <a moz-do-not-send="true"
href="http://www.buildingsmart-tech.org/ifc/IFC4/final/html/link/ifcconversionbasedunitwithoffset.htm">http://www.buildingsmart-tech.org/ifc/IFC4/final/html/link/ifcconversionbasedunitwithoffset.htm</a><br>
<br>
One important consideration: you need to
determine, whether to apply the offset before
or after applying the factor. We decided to
apply it after.<br>
<br>
hope it gives another insight,<br>
<br>
regards<br>
Thomas<br>
<br>
-- <o:p></o:p></p>
<div>
<p class="MsoNormal">Am 08.06.2014 01:46,
schrieb thomas thurman:<o:p></o:p></p>
</div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Addendum for Fahrenheit
discussion. <o:p></o:p></p>
<div>
<div>
<p class="MsoNormal">Comments on current
approach in part 41 and AP 214:<o:p></o:p></p>
<div>
<div>
<div>
<p class="MsoNormal">1-part 41 is
specific that any unit that is
related to a unit specified in
part 41 shall be a
‘conversion_based_unit’.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">2-conversion_based_unit
only converts the magnitude but
does not provide an offset.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">3-The use of
ISO 13584-20 for such a simple
case is long agreed overkill; the
example in part 41 F 4.4 has
EXPRESS<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">errors (<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">a-the
expression_conversion_based_unit
shall be a conversion_based_unit
(see (1) above.) and<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">b-the attribute
redeclaration in e.g.,
named_unit_variable.associated_variable_environment
is invalid.).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">4-AP 242 ed1
did not include a structure to
support Fahrenheit unit exchange.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">5-AP214 used a
context_dependent_unit which is
invalid (see (1) above). As noted
above this was NOT promoted to<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">AP 242.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">6-After several
attempts to discover a URL,URN for
Fahrenheit I gave up and am
proposing that SC4 define its own<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">(NIST has a
guide that includes a definition
of Fahrenheit as a note (I think)
but does not provide a URN or
URL.).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">(There are
multiple conversion calculators on
the web but I am not convinced of
their persistence.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">In any event
use of a conversion calculator
opens up its own can of worms.)<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">==========proposed
solution:===========<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">add a subtype
of conversion_based_unit,
conversion_based_unit_with_offset
to provide the offset.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">=========current:============<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif"">A <b>conversion_based_unit</b> is
a type of </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.named_unit"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">named_unit</span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif""> that
defines a unit on the basis of
a </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">measure_with_unit</span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif"">.</span>
<o:p></o:p></p>
<p class="note"><a
moz-do-not-send="true"
name="note_"><span
style="font-family:"Times","serif"">NOTE </span></a><span
style="font-family:"Times","serif""> The <a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit.value_component"><b>value_component</b></a> attribute
of the <a moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit"><b>measure_with_unit</b></a> defines
the conversion factor.</span><o:p></o:p></p>
<p class="example"><a
moz-do-not-send="true"
name="example_"><span
style="font-family:"Times","serif"">EXAMPLE
An inch is a <b>conversion_based_unit</b>.
It is from the Imperial
system, its name is "inch",
and it can be related to the </span></a><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.si_unit"><b><span
style="font-family:"Times","serif"">si_unit</span></b></a><span
style="font-family:"Times","serif"">, millimetre,
through a </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit"><b><span
style="font-family:"Times","serif"">measure_with_unit</span></b></a><span
style="font-family:"Times","serif""> whose value is
25.4 millimetre. A foot is also
a <b>conversion_based_unit</b>.
It is from the Imperial system,
its name is "foot", and it can
be related to an </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.si_unit"><b><span
style="font-family:"Times","serif"">si_unit</span></b></a><span
style="font-family:"Times","serif"">, millimetre,
either directly or through the
unit called "inch".</span><o:p></o:p></p>
<div>
<p class="MsoNormal"><u><span
style="font-size:13.5pt;font-family:"Times","serif"">EXPRESS
specification:</span></u><o:p></o:p></p>
</div>
<p><code><span
style="font-size:10.0pt">*)</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">ENTITY
conversion_based_unit</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> SUBTYPE
OF (</span></code><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresource_docs%5Cfundamentals_of_product_description_and_support%5Csys%5C18_schema.htm#measure_schema.named_unit"><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif"">named_unit</span></a><code><span
style="font-size:10.0pt">);</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> name
: </span></code><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresource_docs%5Cfundamentals_of_product_description_and_support%5Csys%5C25_schema.htm#support_resource_schema.label"><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif"">label</span></a><code><span
style="font-size:10.0pt">;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> conversion_factor
: </span></code><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresource_docs%5Cfundamentals_of_product_description_and_support%5Csys%5C18_schema.htm#measure_schema.measure_with_unit"><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif"">measure_with_unit</span></a><code><span
style="font-size:10.0pt">;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">WHERE</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> WR1:
SELF\named_unit.dimensions =
derive_dimensional_exponents(conversion_factor\measure_with_unit.unit_component);</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">END_ENTITY;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">(*</span></code><o:p></o:p></p>
<p><u><span
style="font-size:13.5pt;font-family:"Times","serif"">Attribute
definitions:</span></u><o:p></o:p></p>
<p class="expressdescription"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">name: </span></b><span
style="font-size:13.5pt;font-family:"Times","serif"">the </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Csupport_resource_schema%5Csupport_resource_schema.htm#support_resource_schema.label"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">label</span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif""> by
which the <b>conversion_based_unit</b> is
known.</span><o:p></o:p></p>
<p class="expressdescription"><a
moz-do-not-send="true"
name="measure_schema.conversion_based_unit.con"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">conversion_factor: </span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif"">the </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">measure_with_unit</span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif""> that
specifies the physical quantity
from which the <b>conversion_based_unit</b> is
derived.</span><o:p></o:p></p>
<p><u><span
style="font-size:13.5pt;font-family:"Times","serif"">Formal
propositions:</span></u><o:p></o:p></p>
<p class="expressdescription"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">WR1: </span></b><span
style="font-size:13.5pt;font-family:"Times","serif"">The
dimensional exponents shall be
equal to those from the </span><a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.conversion_based_unit.conversion_factor"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">conversion_factor</span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif"">.</span><o:p></o:p></p>
<div>
<p class="MsoNormal"><span
style="font-size:12.0pt"> </span><o:p></o:p></p>
</div>
</div>
<div>
<p class="MsoNormal">=========proposed
addition to part 41=========<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Times","serif"">A <b>conversion_based_unit_with_offset</b> is
a type of <b>conversion_based_unit</b> that
includes a scale offset.</span><o:p></o:p></p>
</div>
<div>
<p class="note"><span
style="font-size:13.5pt;font-family:"Times","serif"">EXAMPLE
A Fahrenheit is a <b>conversion_based_unit_with_offset</b>.
It is from the Imperial system,
its name is “fahrenheit", and it
can be related to the <a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.si_unit"><b>si_unit</b></a>,
degree Celsius, through a <a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresources%5Cmeasure_schema%5Cmeasure_schema.htm#measure_schema.measure_with_unit"><b>measure_with_unit</b></a> whose
value is 1.8 degree Celsius. The
offset is 32 degree Celsius.</span><o:p></o:p></p>
<p><u><span
style="font-size:13.5pt;font-family:"Times","serif"">EXPRESS
specification:</span></u><o:p></o:p></p>
<p><code><span
style="font-size:10.0pt">*)</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">ENTITY
conversion_based_unit_with_offset</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> SUBTYPE
OF (</span></code><code><b><span
style="font-size:10.0pt;font-family:"Times","serif"">conversion_based_unit</span></b></code><code><span
style="font-size:10.0pt">);</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">
offset : <a
moz-do-not-send="true"
href="file:///%5C%5C%5C%5C%5C%5CUsers%5Ctom%5CDocuments%5C2013%5CSMRLv5%5CSMRL_v5_rc5%5Cdata%5Cresource_docs%5Cfundamentals_of_product_description_and_support%5Csys%5C18_schema.htm#measure_schema.measure_with_unit">R</a>EAL;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">WHERE</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt"> WR1:
offset <> 0.0;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">END_ENTITY;</span></code><span
style="font-size:10.0pt;font-family:"Courier
New ,
serif","serif""><br>
</span><code><span
style="font-size:10.0pt">(*</span></code><o:p></o:p></p>
<p><u><span
style="font-size:13.5pt;font-family:"Times","serif"">Attribute
definitions:</span></u><o:p></o:p></p>
<p class="expressdescription"><a
moz-do-not-send="true"
name="measure_schema.conversion_based_unit.nam"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">offset: </span></b></a><span
style="font-size:13.5pt;font-family:"Times","serif"">the value
of the offset represented in the
units of the conversion_factor
inherited from
the conversion_based_unit.</span><o:p></o:p></p>
<p class="expressdescription"><u><span
style="font-size:13.5pt;font-family:"Times","serif"">Formal
propositions:</span></u><o:p></o:p></p>
<p class="expressdescription"><a
moz-do-not-send="true"
name="measure_schema.conversion_based_unit.wr:"><b><span
style="font-size:13.5pt;font-family:"Times","serif"">WR1: The
offset shall not be zero.</span></b></a><o:p></o:p></p>
<div>
<p class="MsoNormal">Note: If the
offset is zero, then the
supertype <b><span
style="font-family:"Times","serif"">conversion_based_unit
</span></b><span
style="font-family:"Times","serif"">is
used.</span><o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal">=========end
proposed addition to part
41=========<o:p></o:p></p>
</div>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">On Jun 6, 2014,
at 3:29 PM, Martin Hardwick <<a
moz-do-not-send="true"
href="mailto:hardwick@steptools.com">hardwick@steptools.com</a>>
wrote:<o:p></o:p></p>
</div>
<p class="MsoNormal"><br>
<br>
<br>
<br>
<o:p></o:p></p>
<div>
<div
style="margin-left:-.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-align:center"
align="center"><b><span
style="font-size:16.0pt">P21
e3 DIS Testing</span></b><o:p></o:p></p>
</div>
<div
style="margin-left:-.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-align:center"
align="center"><span
style="font-size:14.0pt">Minutes
of June 5, 2104 Telecon</span><o:p></o:p></p>
</div>
<h2>Attendees<o:p></o:p></h2>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Martin
Hardwick
<a moz-do-not-send="true"
href="mailto:hardwick@steptools.com"><hardwick@steptools.com></a>
<br>
Robert Lipman <a
moz-do-not-send="true"
href="mailto:robert.lipman@nist.gov"><robert.lipman@nist.gov></a>
<br>
Michael Benda <a
moz-do-not-send="true"
href="mailto:mjbenda@rockwellcollins.com"><mjbenda@rockwellcollins.com></a>
<br>
Hedlind Mikael <a
moz-do-not-send="true"
href="mailto:mikael.hedlind@scania.com"><mikael.hedlind@scania.com></a>
<br>
Dave Loffredo <a
moz-do-not-send="true"
href="mailto:loffredo@steptools.com"><loffredo@steptools.com></a>
<br>
Ed Paff <a
moz-do-not-send="true"
href="mailto:ejp@transcendata.com"><ejp@transcendata.com></a>
<br>
Tom Thurman <a
moz-do-not-send="true"
href="mailto:thomas.r.thurman@imonmail.com"><thomas.r.thurman@imonmail.com></a><o:p></o:p></p>
<h2>Apologies for Absence<o:p></o:p></h2>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Jochen
Fritz
<a moz-do-not-send="true"
href="mailto:jfritz@steptools.com"><jfritz@steptools.com></a>
<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Nicolas
Figay
<a moz-do-not-send="true"
href="mailto:nicolas.figay@eads.net"><nicolas.figay@eads.net></a>
<br>
<br>
<br>
<br>
<o:p></o:p></p>
<h2>PMI Splitting<o:p></o:p></h2>
<p class="htmlbody">ITI has split
the sp3_boxy file produced by NIST
into a geometry file and a pmi
file. STEP Tools has viewed the
geometry file and is working on a
viewer for the separated pmi file.
The two files and the original
NIST data can be found at the
following URL:<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><a
moz-do-not-send="true"
href="ftp://www.steptools.com/private/P21e3_DIS_testing/PMI/">ftp://www.steptools.com/private/P21e3_DIS_testing/PMI/</a><o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">STEP Tools is
sponsoring the development of open
source programs to split and merge
P21 files using the Edition 3
specification. The programs are
available at the following URL:
<a moz-do-not-send="true"
href="http://tinyurl.com/thundercode">http://tinyurl.com/thundercode</a>.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<h2>ZIP Assemblies<o:p></o:p></h2>
<p class="htmlbody">No visible
progress has been made on this
test case since the last telecom,
but the PMI merge and split code
is being updated to handle this
case as well.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><a
moz-do-not-send="true"
href="ftp://www.steptools.com/private/P21e3_DIS_testing/ZIP_Assembly/">ftp://www.steptools.com/private/P21e3_DIS_testing/ZIP_Assembly/</a><o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">In the last
telecom:<o:p></o:p></p>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in"><span
style="font-family:Symbol">·</span><span
style="font-size:7.0pt">
</span>We decided the sub-tree
directory names should include
the NUAO identifier(s) for their
corresponding node in the
assembly tree.<o:p></o:p></p>
</div>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in"><span
style="font-family:Symbol">·</span><span
style="font-size:7.0pt">
</span>We learned that the LZMA
algorithm has been shown to make
STEP files three times more
compressed than the more
commonly used deflate algorithm,
but at the cost of an increase
in the compression time.<o:p></o:p></p>
</div>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in"><span
style="font-family:Symbol">·</span><span
style="font-size:7.0pt">
</span>We learned that each
compressed file is required to
document the algorithm used for
its compression in its header
and that different components in
the same ZIP can used different
compression algorithms.<o:p></o:p></p>
</div>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in"><span
style="font-family:Symbol">·</span><span
style="font-size:7.0pt">
</span>We recommended that the
choice of the best compression
algorithm should be left to the
end user and that the standard
should be silent on the matter.
<o:p></o:p></p>
</div>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><b> </b><o:p></o:p></p>
<h2>Unit Definitions<o:p></o:p></h2>
<p class="htmlbody">The unit
definitions have been merged into
a single file called units.stp.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><a
moz-do-not-send="true"
href="ftp://www.steptools.com/private/P21e3_DIS_testing/Units/">ftp://www.steptools.com/private/P21e3_DIS_testing/Units/</a><o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">We continued our
discussion on whether unit
references should be encoded as a
URL or a URN. The following two
lines of code show equivalent
URL’s and URN’s.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><a
moz-do-not-send="true"
href="http://standards.iso.org/iso/10303/tech/reference_data/41/si_base_units.stp#METRE"><http://standards.iso.org/iso/10303/tech/reference_data/41/si_base_units.stp#METRE></a>;<o:p></o:p></p>
<p class="htmlbody"><urn:iso:std:iso:10303:-41:tech:unit:metre>;<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<div
style="margin-left:63.0pt;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-63.0pt">Explanation
of URN: <o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">urn
Indicates this URI is a URN,
instead of the more common URL
(http)<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">iso
URN namespace (other examples
are oid, usbn)<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">std
ISO standard <o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">iso
originating organization (other
examples are iec, iso-ies,
iso-cie)<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">10303
STEP standard
<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">-41
part of multipart standard
(hyphens required)
<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in">Tech
associated or embedded resource
defined by committee that
created the standard
<o:p></o:p></p>
</div>
<div
style="margin-left:1.0in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-1.0in"><the
rest>
unspecified -- controlled by
committee.<o:p></o:p></p>
</div>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">In the above
example, the URN has small
advantage over the URL but perhaps
the following URN will be
acceptable because a file does not
have to exist to define a URN.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><urn:iso:metre>;<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">It is also
conceivable that the following URN
might be acceptable even though
there are currently small
technical issues stopping the
deployment of unit definitions for
a Fahrenheit measure in a STEP
file.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><urn:iso:Fahrenheit>;
<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">We further
discussed the requirements if all
the unit definitions are to be
defined in STEP files. The
definition of literal constants
such as PI, and EXPRESS constants
such as negri_pi, have both led to
extensive additions to the edition
3 format for which other strong
use cases are currently lacking.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">On the other
hand the problem might be that we
have not been sufficiently
ambitious. It was pointed out that
if constants can be defined then
we are close to allowing
expressions to be defined. The use
of the PLIB schema for expressions
has never been very satisfactory
because the expressions are too
hard to read when encoded into the
STEP files. However, if Part 21
has an expression evaluation
capability (probably in the
anchors) then potential STEP
applications such as parametrics
and construction history might
become more tractable. One
interesting possibility might be
to use Modelica as the expression
language.<br>
<br>
<br>
<br>
<o:p></o:p></p>
<h2>Digital Signatures<o:p></o:p></h2>
<p class="htmlbody">STEP Tools gave
a demonstration of how to make a
digital signature using a private
key and a signing certificate and
how to verify that a file has not
been edited since it was signed
using a public key.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody"><a
moz-do-not-send="true"
href="ftp://www.steptools.com/private/P21e3_DIS_testing/Digital_signatures/">ftp://www.steptools.com/private/P21e3_DIS_testing/Digital_signatures/</a><o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">We discussed
white space and the issues that
might arise if a file is read into
Notepad/Wordpad and converted from
line-feeds to carriage returns or
vice versa. These characters are
explicitly excluded from the Part
21 character set so they will not
be included when computing and
verifying the hash value.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">We discussed
supporting multiple signatures.
The easiest procedure is for each
signature to be applied to all of
the characters that precede that
signature. Thus each new signee is
also verifying the signature of
the previous signees.
<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<p class="htmlbody">For this to be
consistent it would be best if the
signatures came after the
END-ISO-10303-21 keyword as shown
in the example on the ftp site.<o:p></o:p></p>
<p class="htmlbody"> <o:p></o:p></p>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in"><span
style="font-family:Symbol">·</span><span
style="font-size:7.0pt">
</span>The next conference call
will be held on Friday June 27
at 4PM Paris, 3PM London, 10AM
New York and 7AM Seattle.<o:p></o:p></p>
</div>
<p class="htmlbody"> <o:p></o:p></p>
<h2>Action Items<o:p></o:p></h2>
<p class="htmlbody"
style="margin-left:.5in;text-indent:-.25in">1.<span
style="font-size:7.0pt">
</span>Complete the first ZIP
assembly example.<o:p></o:p></p>
<p class="htmlbody"
style="margin-left:.5in;text-indent:-.25in">2.<span
style="font-size:7.0pt">
</span>Consider the best approach
for unit definitions: URN’s or
URLs’?<o:p></o:p></p>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in">3.<span
style="font-size:7.0pt">
</span>Consider if Edition 3
should offer any support to the
definition of parametrics and if
so how?<o:p></o:p></p>
</div>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in">4.<span
style="font-size:7.0pt">
</span>Extend the digital
signatures example to include
the creation of signing
certificates.<o:p></o:p></p>
</div>
<div
style="margin-left:.5in;margin-right:-.5in">
<p class="MsoNormal"
style="text-indent:-.25in">5.<span
style="font-size:7.0pt">
</span>Demonstrate signing at
one site (ITI) and verification
at another site (STEP Tools).<o:p></o:p></p>
</div>
<div
style="margin-left:.25in;margin-right:-.5in">
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div
style="margin-left:.25in;margin-right:-.5in">
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<p class="MsoNormal"
style="text-autospace:ideograph-other">As
recorded by Martin Hardwick
<a moz-do-not-send="true"
href="mailto:hardwick@steptools.com"><hardwick@steptools.com></a>
<br>
<br>
<br>
<br>
<o:p></o:p></p>
</div>
<p class="MsoNormal"
style="text-autospace:ideograph-other"><span
style="font-size:12.0pt"><Minutes_p21e3_DIS_conference_call_05062014.docx>_______________________________________________<br>
wg11 mailing list<br>
<a moz-do-not-send="true"
href="mailto:wg11@steptools.com">wg11@steptools.com</a><br>
<a moz-do-not-send="true"
href="http://lists.steptools.com/mailman/listinfo/wg11">http://lists.steptools.com/mailman/listinfo/wg11</a></span><o:p></o:p></p>
</div>
<p class="MsoNormal"
style="text-autospace:ideograph-other"><span
style="font-size:12.0pt"> </span><o:p></o:p></p>
<div>
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style="text-autospace:ideograph-other"><span
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style="font-size:12.0pt"><br>
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<br>
</span><o:p></o:p></p>
</div>
<p class="MsoNormal"
style="text-autospace:ideograph-other"><span
style="font-size:12.0pt"> </span><o:p></o:p></p>
</div>
</div>
</div>
<p class="MsoNormal"
style="text-autospace:ideograph-other"><span
style="font-size:12.0pt"><br>
<br>
<br>
<br>
<br>
</span><o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>wg11 mailing list<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:wg11@steptools.com">wg11@steptools.com</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://lists.steptools.com/mailman/listinfo/wg11">http://lists.steptools.com/mailman/listinfo/wg11</a><o:p></o:p></pre>
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</span><o:p></o:p></p>
<p>beste Grüße / kind regards<br>
<br>
Dr.-Ing. Thomas Liebich<br>
Geschäftsführer / Director <o:p></o:p></p>
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<p><span style="font-size:10.0pt">AEC3
Deutschland GmbH<br>
AG München, Handelsregister HRB
164221<br>
Geschäftsführer: Dr. Thomas
Liebich, Kerstin Hausknecht</span><o:p></o:p></p>
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<p><span style="font-size:10.0pt">Wendl-Dietrich-Str.
16, D-80634 München<br>
Tel: +49-89-18703223<br>
Fax: +49-89-18703224</span><o:p></o:p></p>
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<p><span style="font-size:10.0pt">E-Mail:
<a moz-do-not-send="true"
href="mailto:tl@aec3.de">tl@aec3.de</a><br>
Internet: <a
moz-do-not-send="true"
href="http://www.aec3.de">www.aec3.de</a><br>
</span><o:p></o:p></p>
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<pre>_______________________________________________<o:p></o:p></pre>
<pre>wg11 mailing list<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:wg11@steptools.com">wg11@steptools.com</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://lists.steptools.com/mailman/listinfo/wg11">http://lists.steptools.com/mailman/listinfo/wg11</a><o:p></o:p></pre>
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