[osis-core] Options for <identifier>

[Todd Tillinghast]

Steve, Chris, and Troy,

Assuming we are all on the same page regarding the necessity of a
mechanism to indicate the _naming authority_ for an indetifier, we have
the following syntax options:

1) <identifier type="prefix"
osisTextID="true">identifier_value</identifier> (where osisTextID is
optional, defaults to "false", and indicates that the current identifier
is the "unique" identifier if "true" AND type defaults to "private")

2) <identifier type="unique">prefix:identifier_value</identifier> (where
the type attribute indicates the type of identifier this is not the
_name authority_ that the value of the identifier belongs to.)

3) <identifier type="OSIS or
prefix">prefix:identifier_value</identifier> (where prefix can be either
specified in the type attribute or in the body AND type="OSIS" indicates
the type of identifier and type=" other than OSIS " indicates the _name
authority_ that the value belongs to.)

Option 1#: 
a) clearly specifies the _naming authority_
b) uses the type attribute to specify not the type of the <identifier>
element but the _naming authority_ of the value it contains.
c) specifies a boolean for osisTextID which limits future options
d) is inconsistent with the prefix mechanism used throughout the schema.

Option #2:
a) clearly specifies the _naming authority_
b) uses the type attribute to specify the type of the <identifier> and
leaves the door open for future type values consistent with other type
attributes in the rest of the schema.
d) is consistent with the prefix mechanism used throughout the schema

Option #3: 
a) provides multiple mechanisms to express the prefix/_naming authority_
b) assigns a mixed meaning to the type attribute (both the type of the
element <identifier> and the _naming authority_ of the contained value.


In my view:
Option #3 should be ruled out because of its inconsistency with itself.
Option #2 is superior to option #1 for the reasons above.

Is there a reason why you would not choose options #1 and #2 over #3?

Is there a reason why you would prefer option #1 to option #2?

Todd