PGalias

new

Create one alias object per question (and per PGcore object since there is a unique PGcore per question.)
Check that information is intact
Construct unique id stub seeds -- the id stub seed is for this PGalias object which is
     attached to all the resource files (except equations) for this question.
Maintain list of links to external resources

make_alias

This is the workhorse of the PGalias module. It's front end is alias() in PG.pl.

make_alias magically takes a name of an external resource ( html file, png file, etc.) and creates full directory addresses and uri's appropriate to the current displayMode. It also does any necessary conversions behind the scenes.

Returns the uri of the resource.