On Jul 11, 2016, at 4:32 PM, Kyle Banerjee <[log in to unmask]> wrote:
> Is the idea that this new field would be stored as MARC in the system (the
> If so, the 9xx solution already suggested is probably the way to go if the
> 008 route suggested earlier won't work for you. Otherwise, you run a risk
> that some form of record maintenance will blow out all your changes.
> The actual use case you have in mind makes a big difference in what paths
> make sense, so more detail might be helpful.
Thank you, one & all, for the input & feedback. After thinking about it for a while, I believe I will save my normalized dates in a local (9xx) field of some sort.
My use case? As a part of the "Catholic Portal", I aggregate many different types of metadata and essentially create a union catalog of rare and infrequently held materials of a Catholic nature.  In an effort to measure “rarity” I've counted and tabulated the frequency of a given title in WorldCat. I now want to measure the age of the materials in the collection. To do that I need to normalize dates and evaluate them. Ideally I would save the normalized dates back in MARC and give the MARC back to Portal members libraries, but since there is really no standard field for such a value, anything I choose is all but arbitrary. I’ll use some 9xx field, just to make things easy. I can always (and easily) change it later.
 "Catholic Portal” - http://www.catholicresearch.net
Eric Lease Morgan