1.  Map Attribute

  map     : arcspec +
          ;
  arcspec : gispec
          | attspec
          | conspec
          | control
          ;

The value is structured as a whitespace-separated sequence of tokens,
logically organized as pairs.  Each token is either a name or a name
prefixed with '#'.  Unprefixed names identify attributes, and prefixed
names identify control variables.  The first token in each pair, called
the 'target' for short, pertains to the archetype; the second, called
the 'source', to the document; each pair taken together is a statement
regarding some aspect of the architectural instance.

2.  Generic Identifier

  gispec  : '#GI'  gisrc
          ;
  gisrc   : NAME
          | '#CONTENT'
          | '#BRIDGE'
          ;

If the rules in effect cause the element to be taken as architectural,
the source generic identifier is taken for the target by default.  The
'#GI' control variable overrides this default specification as follows:

  - If the source is a name, the value of the attribute with that name
    is taken as the archetype GI.
  - '#CONTENT' selects the syntactic data content as the source of the
    element type name.  The content must meet the requirements of a
    valid name after the removal of surrounding white space.
  - '#BRIDGE' selects the default "bridge element name" associated with
    the architecture.

3.  Attribute Specification

  attspec : NAME  attsrc
          ;
  attsrc  : NAME
          | '#GI'
          | '#CONTENT'
          | '#IMPLIED'
          ;

An attribute specification controls an attribute, named by the target,
in the archetype element.

  - If the source is also a name, it is that of the attribute in the
    start-tag whose value will be specified for the target.
  - The control variables '#GI' and '#CONTENT' refer to the generic
    identifier and syntactic data content respectively as the value
    specification.
  - The control variable '#IMPLIED' means that an attribute with this
    name is not asserted in the archetype if other rules in effect would
    otherwise cause one such in the source to be taken as architectural.

3.  Content Specification

  conspec : '#CONTENT'  consrc
          ;
  consrc  : NAME
          | '#GI'
          | '#DATA'
          | '#ELEM'
          ;

The '#CONTENT' control variable can be used in the target position to
override the default disposition of source content as target content.

  NAME   : The value of the named attribute provides the content.
  '#GI'  : The generic identifier, interpreted as a literal string.
  '#DATA': Immediate syntactic data content only; all subelements
           are unconditionally treated as non-architectural.
  '#ELEM': All immmediate syntactic data content is suppressed; the
           content is determined solely by the processing of subelements.

4.  Control Specifications

  control : CONTROL  value
          ;
  value   : CONTROL
          | NAME
          ;

Control specifications affect the overall state of architectural
processing.  All such values are "inherited", in that settings are
propagated down the element hierarchy, and can be overridden only by
imeediate explicit specification in the map attribute.  Each control has
its own set of permissible source values.

4a.  #SEP - Element Separator
  Permitted source values:
   #NONE - the empty string '' (default)
   #SPACE - the string " "

The #SEP control affects the "spacing" of subelements within the parent
context when the processing of adjacent subelements causes element
boundaries to be lost: the appropriate string is inserted.  This can be
activated only when the parent context has specified #ELEM processing of
content.  (Extension: a NAME instead of a control variable addresses the
value of the attribute as the seprator string.)


4b.  #AUTO - Automatic disposition of source text
  Permitted source values
   #ON (default) - all content is architectural.
   #OFF - no content is architectural unless explicitly identified.

4c.  #DERIV - Inherit from another map attribute

4d.  #BRIDGE

4e.  #INCL

4f.  #EXCL

4g.  #PI

4h.  #COM

4i.  #SPEC

4j.  #DTD

4k.  #MAP

5.  Processing Algorithm

  Construct new 'state' on start-tag event (destroy on endtag event).
  Inherit default values.
  Test for architectural declaration attribute
    process if necessary
  Test for map attribute -
    parse
    update defaults
  Construct starttag