[Koha] Creative re-purposing of major fields

[hansbkk at gmail.com]

I'm currently using Koha to catalog a collection of mostly non-book resources
at my school, many of which are stored on physical DVDs and/or online available
for download.

I'm thinking of re-purposing some of Koha's major data fields where their usual
meaning isn't all that relevant to this project. For example, I plan to create
my call numbers so they are sufficient to identify the physical location within
a given branch.  This will free up "Collection" and "Shelf Location" for other,
more relevant classifications.

Before I start mapping this out, I first want to get feedback that I'm not way
off-track thinking this way. First question:

I believe that the original intention was a hierarchy for physical location:
  Home branch -->  Collection --> Shelving location --> Call number

If I re-purpose these fields so that e.g. Collection is used for distinguishing
between "Disc-Data" vs "Disc-Video" vs "Disc-Mixed", is their any remnant of the
above original hierarchy that will cause trouble? Is Collection completely
independent of Branch in the database and UI design, or is there some
enforcement of one Collection being "contained" within a Branch?

Same question of course with Shelving location relative to both Collection and
Branch - say I used this field to map to "Age Appropriateness" (Adult-only,
Young adult, Juvenile, Early learners). Note that the Age factor is a biblio
level one, while many biblios will have both a Data and a Video disc - a member
may want to borrow only one or both.

Next question is - are these easily used as search factors in the OPAC, so
members can browse a subject only looking at VDO discs suitable for Juveniles?

I don't mind a bit of customization, assuming this can be preserved across
upgrades.

Obviously the latter fits well within Item type, but this seems designed for
factors that are affect circulation policies - loan duration, charges etc.

Last question - is that field even available as a search limiter?

I could use "Film-Disc-Data" and "Film-Disc-Video" or "Film-Disc-Mixed", but
many members don't care about the distinction, so I'm thinking it would be
simplest to just use "Film" as a monolithic category and not worry about the
media details there; as I'd rather have them manually pick and choose among
their results than have to run multiple searches.

Obviously besides having the direct questions addressed, any general ideas or
suggestions would be most welcome.