Re: [xml-dev] Random Access XML

[John Cowan <cowan@mercury.ccil.org>]

rjelliffe scripsit:

> 1) For a start, we need to be able to know whether "<" "</" and ">" are  
> tag delimiters without knowing context. So we must ban direct use of "<"  
> and ">" in attributes and also get rid of CDATA sections. We should get  
> rid of comments and PIs too, for the same reasons. (Actually, we only  
> need to ban comments and PIs from after the first start tag. For other  
> reasons, we might like to treat the first start-tag and before it  
> specially.)

Of course, random < is already banned everywhere, so if you ban > in
character content as well as attribute values, you get full reversibility:
each of <, </, <?, <!--, >, />, and --> is guaranteed to be the open or
close delimiter of a markup construct.

MicroXML already bans > in character content so that it doesn't have to
special-case ]]>, as required for full XML compatibility.  The only reason
it doesn't ban > in attribute values is that they are required for
compatibility with Canonical XML.

> 3) The generic identifier would have to be more like an XPath.

This could be achieved by convention, using a legal but rarely
employed delimiter like U+00B7 MIDDLE DOT, or any of the vast number of
delimiters allowed by XML 1.0 Fifth Edition.

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