[sc34wg3] CTM - Keywords reserved or not?

Lars Heuer heuer at semagia.com
Thu Nov 22 08:54:53 EST 2007

> CTM would then steal just one possible item identifier "def" which
> cannot be used to start a topic block.

I investigated this stuff a bit further and came to the conclusion
that "end" as topic identifier is also a bad idea (at least as
identifier to start a topic block). The problem is, "end" may be used
within a template definition:

    def tpl($arg)


Here we have a problem since it is not obvious if the user meant

  def tpl($arg)

      end      # Topic part of the template



  def tpl($arg)
               # Empty template (The problem would also be there
               # if the template weren't empty).


I propose to disallow "def" and "end" as start of a topic block.

So far I wasn't able to detect ambiguous situations with "isa", "ako",
and "as".

Even if it does not make sense, the following construct is, for
example, unambiguous:

    isa isa isa ako isa as: http://www.example.org/

    isa     # Topic identifier
       isa isa      # type instance relationship
       ako isa      # supertype subtype relationship
       as: http://www.example.org/  # Occurrence

   %import http://www.example.org/ as as
                                   ^   ^
                         Keyword 'as'  Identifier 'as'

Best regards,

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