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<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff
size=2>Paul,</FONT></SPAN></DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff size=2>I
fully agree with you, that the T.38 (1998) asn.1 and the Revision of T.38 (2002)
asn.1 needs to be backwards compatible. </FONT></SPAN></DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff
size=2>Regards,</FONT></SPAN></DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff size=2>Karl
Klaghofer</FONT></SPAN></DIV>
<DIV><SPAN class=420224008-14032003><FONT face=Arial color=#0000ff
size=2>Siemens</FONT></SPAN></DIV>
<BLOCKQUOTE>
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Ursprüngliche Nachricht-----<BR><B>Von:</B> Paul E. Jones
[mailto:paulej@PACKETIZER.COM]<BR><B>Gesendet:</B> Montag, 3. März 2003
03:21<BR><B>An:</B> ITU-SG16@echo.jf.INTEL.COM<BR><B>Betreff:</B> T.38
potentially broken by recent Corrigendum<BR><BR></FONT></DIV>
<DIV><FONT face=Arial>
<DIV><FONT face=Arial>Folks,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I just recently discovered that the ITU-T published a
corrigendum to T.38 (1998) that apparently breaks backward compatibility for
all T.38 devices currently deployed that follow the original 1998
specifications. The particular document in question is Corrigendum 1,
which was approved in 2000 and subsequently published in May 2001. You
can download the corrigendum document for free from this
site:</FONT></DIV><FONT face=Arial><A
href="http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-T.38">http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-T.38</A></FONT>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>The issue at hand is a change in the ASN.1 syntax found
in Annex A/T.38. The particular data structure is shown
here:</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV>Data-Field ::= SEQUENCE OF SEQUENCE<BR>{<BR>
field-type ENUMERATED<BR> {<BR> hdlc-data,<BR> hdlc-sig-end,<BR> hdlc-fcs-OK,<BR> hdlc-fcs-BAD,<BR> hdlc-fcs-OK-sig-end,<BR> hdlc-fcs-BAD-sig-end,<BR> t4-non-ecm-data,<BR> t4-non-ecm-sig-end<U><FONT
color=#ff0000>,</FONT></U><BR> <U><FONT
color=#ff0000>...</FONT></U><BR> },<BR> field-data OCTET
STRING (SIZE(1..65535)) OPTIONAL<BR>}</DIV>
<DIV><FONT face=Arial></FONT> </DIV></BLOCKQUOTE>
<DIV dir=ltr><FONT face=Arial>The syntactical change was the addition of an
ellipsis at the end of the ENUMERATED "field-type". In the published
1998 specification, this ellipsis did not exist.</FONT></DIV>
<DIV dir=ltr><FONT face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT face=Arial>What I would like to know is whether this change
impacts your product or not. I am aware of many deployed devices on the
market today that employs the 1998 syntax without this ellipsis. I would
like to find out to what extent this change is going to present problems
for companies represented on various lists and, if I get
sufficient support, I want to take a contribution to the ITU-T SG16 meeting in
May to try to resolve this problem in such a way as to not break backward
compatibility and interoperability.</FONT></DIV>
<DIV dir=ltr><FONT face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT face=Arial>I am looking forward to your
replies.</FONT></DIV>
<DIV dir=ltr><FONT face=Arial></FONT> </DIV>
<DIV dir=ltr><FONT face=Arial>Kindest Regards,</FONT></DIV>
<DIV dir=ltr><FONT face=Arial>Paul E.
Jones</FONT></DIV></FONT></DIV>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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