[osis-core] Insertion of "identifiers" into text.

[Todd Tillinghast]

Some time ago Troy brought up the question of how to encode "identifies"
in text.  I believe we concluded at the time that a reference element
with a value from the appropriate reference system (taxonomy) could be
used.

The question I have is how do associate an identifier with an element.
For example if I wanted to say that a paragraph or other block of text
is about "anger".  

The best I can come up with is a <note> element with an osisRef to
desired text.  (Similar to a cross reference)

This will work with scripture text with a well defined reference system,
but for non-Biblical text that often does not have osisIDs this becomes
an issue.  (This would likely be resolved if XPath/XPointer like syntax
were allowed in a reference or reference like element.)

Todd