Re: Element Structure for XML (Clause 7)

At , Michael Sperberg-McQueen , W3C SGML Working Group, wrote

>>>The one thing I have most missed in PIs as currently constituted is a
>>>reasonably simple, mostly reliable method for different applications
>>>to avoid tripping over each other's PIs.  I have the impression
>>>that some applications try to make all of their PIs begin with
>>>some keyword (say, the name of the application), so that they can
>>>readily tell, by looking just at the first token of the PI, whether
>>>the PI could possibly be theirs or not.  So a document with
>>>  <?TeX \vskip 0.75in>
>>>  <?WScript .sp 4.5 a>
>>>  <?teihtml filebreak>
>>>could be processed by applications which recognize the keywords
>>>TeX, WScript, and teihtml, and each application can know from the
>>>keywords which PIs it should pay attention to, and which it can
>>>(and should!) ignore.

But what happens when there is a new non-backward compatible variant for the
language - do you have to have a new name to distinguish the new variant, or
do you have to have some form of version control statement? What worries me
is how to processes XML documents placed in the BNC 20 years after their
creation if they contain processing instructions.
Martin Bryan, The SGML Centre, Churchdown, Glos. GL3 2PU, UK 
Phone/Fax: +44 1452 714029   WWW home page: http://www.u-net.com/~sgml/