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<!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML//EN"> <HTML> <HEAD> <META content="text/html; charset=iso-8859-1" http-equiv=Content-Type> <META content='"MSHTML 4.72.3110.7"' name=GENERATOR> </HEAD> <BODY bgColor=#ffffff style="FONT: 10pt Arial; MARGIN-LEFT: 2px; MARGIN-TOP: 2px"> <DIV>Michael wrote,<BR><BR>   "An IPP object MUST be able to accept any of the attribute syntaxes<BR>    defined in Section 4.1, including their full range and any<BR>    value tags that are undefined in this document, in any operation<BR>    in which a client may supply attributes or the system ..."<BR><BR>The places where one may encounter a value tag in an IPP packet are the same places where one may encounter attribute group tags.  The IPP documentation states that IPP applications should accept and ignore new/unknown attribute group tags.  This is a reasonable requirement because whenever my application runs into an "unknown" tag it assumes it's a new attribute group.  But if we allow the flexibility that I think you're proposing, parsing an IPP packet becomes much more complex and dangerous.  When I run into an "unknown tag", am I looking at ..</DIV> <DIV> </DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">a) The start of a new attribute group?</FONT></DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">b) An attribute of the current attribute group with an unknown syntax?</FONT></DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">c) A malformed packet?</FONT></DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">d) If two unknown tags are next to each other are they t</FONT><FONT style="BACKGROUND-COLOR: #ffffff">wo empty new attribute groups or a new syntax and its attribute name length?</FONT></DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">e) etc.</FONT></DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff"></FONT> </DIV> <DIV><FONT style="BACKGROUND-COLOR: #ffffff">-Hugo</FONT></DIV></BODY></HTML>