[development] versioned schema?

[Peter Wolanin]

A quick thought in terms of the Schema API and writing system/module updates:

As far as I understand, on e shouldn't use functions like
drupal_install_schema() in update functions since one cannot rely upon
which version of the schema presently exists int he .schema file.

To me this suggests that there should be a way having several
different schema in the .schema file with different version numbers.
Then functions like drupal_install_schema() could take an optional
argument for the schema version.   Does that make sense?

-Peter