expanding =begin

From perlpodspec:

   "=begin formatname"
       This marks the following paragraphs (until the matching "=end
       formatname") as being for some special kind of processing.  Unless
       "formatname" begins with a colon, the contained non‐command
       paragraphs are data paragraphs.  But if "formatname" does begin
       with a colon, then non‐command paragraphs are ordinary paragraphs
       or data paragraphs.  This is discussed in detail in the section
       "About Data Paragraphs and "=begin/=end" Regions".

       It is advised that formatnames match the regexp
       "m/\A:?[−a−zA−Z0−9_]+\z/".  Implementors should anticipate future
       expansion in the semantics and syntax of the first parameter to
       "=begin"/"=end"/"=for".

I'd like to extend this definition a bit.  I would replace the second paragraph
with:

   "=begin formatname"
   "=begin formatname parameter"
       This marks the following paragraphs (until the matching "=end
       formatname") as being for some special kind of processing.  Unless
       "formatname" begins with a colon, the contained non‐command
       paragraphs are data paragraphs.  But if "formatname" does begin
       with a colon, then non‐command paragraphs are ordinary paragraphs
       or data paragraphs.  This is discussed in detail in the section
       "About Data Paragraphs and "=begin/=end" Regions".

       It is advised that formatnames match the regexp
       "m/\A:?[−a−zA−Z0−9_]+\z/".  Everything following whitespace after the
       formatname is a parameter that may be used by the formatter when dealing
       with this region.  Implementors should anticipate future
       expansion in the semantics and syntax of the first parameter to
       "=begin"/"=end"/"=for".

This allows for constructions like:

  =begin syntax javascript

  =end syntax

...or...

  =begin table width(10) height(9)

  =end table

...or...

  =begin dialect Pod6

  =end dialect

I believe several parsers already allow this implicitly.

-- 
rjbs