[osis-core] When an osisID is not an osisID?

[Harry Plantinga]

> Proposal:
>
> For translations/texts  that do not follow a canonical reference system
> but that do refer to such systems to document particular places in the
> text, the structure of the text should be encoded but references to the
> external system, whether on an element or by milestone appearing in
> running text, should be using the osisRef attribute of type osisRef.
>
> Patrick

There are two general approaches to handling differences in bible
reference schemes:

1.  Use a single canonical reference scheme and map between it and
other schemes.  E.g. declare the scheme used by the NRSVA to be 'canonical'.
THen, if you are marking up the LXX, for Psalm 21 you'd have to use
the osisID Psalm.20 (or whatever).

2.  Use different reference schemes and define mappings between them.
In the LXX, identify "Psalm 21" as "bible.lxx.psalm.21".  Somewhere,
you'd have a mapping that would be able to identify that as
bible.nrsva.psalm.20.

I would like to be clear on whether there is a single canonical bible
reference scheme, psalm.20, or several, bible.lxx.psalm.21,
bible.nrsva.psalm.20, etc.  If the latter, is there a way to specify
a mapping?

-Harry