[imps] Tree construction test in undocumented format

[James Graham]

Anne van Kesteren wrote:
> On Fri, 04 Apr 2008 18:14:13 +0200, Henri Sivonen <hsivonen at iki.fi> wrote:
>> How about <!DOCTYPE %name %public_id "%system_id> where %foo_id is 
>> either a double-quoted string or the string 'null' without quotes.
>>
>> But if both are null, use
>> <!DOCTYPE %name>
> 
> Sure, lets do that.

I would prefer not to use the unmatched quote, since some editors insert double 
quotes automatically.

Is there a problem with just doing:
<!DOCTYPE %name "%public_id" "%system_id">

If we need to distinguish the null case from the empty string case we could 
just, as suggested, replace the whole quoted thing with unquoted null in those 
cases.

(the no-public/system case should still be <!DOCTYPE %name>)

-- 
"Eternity's a terrible thought. I mean, where's it all going to end?"
  -- Tom Stoppard, Rosencrantz and Guildenstern are Dead