Proposed amendment to holdings schema version 1.3

The proposal below, to amend the holdings schema,
is from LC (in coordination with other interested
parties) and is needed for MODS.  The MODS
community has expressed a requirement for holdings
information, and would like to accomodate this
requirement using the Z39.50 holdings format. Part
1 of the proposal is necessary in order to do
that. The proposal has three parts; only part 1 is
critical for  MODS utilization of the format.

There are some other changes needed, but this one
(and part 1 only) is the most pressing,  and we'll
propose the others later.

Background:
in the holdings schema, version 1.3
(http://lcweb.loc.gov/z3950/agency/defns/holdings1-3.html)
the datatype PhysicalFormInfo, newly added in this
version,  consists of the single element formCode.
It's definition consists of a list of physical
forms:
    microform ('hh'),
   microform aperture card ('ha'),
   microfilm cartridge ('hb'),
    etc.

where, for example, "microform" is a
human-readable description where 'hh' is the code,
whose value the element is to assume.

Proposal:
(1) structure PhysicalFormInfo into two
subelements: 'code' and 'text'  so that one or
both can be supplied, that is (1) a value from the
controlled list of codes, and/or (2) an
uncontrolled  text string.

(2) Change the defintion of physicalFormDesignator
in BibPart from text to PhysicalFormInfo. The
element physicalFormDesignator In BibPart, which
has been retained for backwards compatibility,  is
defined as string and its definition includes the
list of physical form values, the same list as in
the newly added element PhysicalFormInfo. The
purpose of this part of the  proposal is to avoid
listing  the table twice.

(3) Reference the table of codes in the NISO
standard rather than list them. The list of
designators is the same as in Z39.71: Holdings
Statements for Bibliographic Items
(http://www.niso.org/standards/resources/z39-71.pdf
) , table 3.3, Physical Form Designators.

Please comment on this proposal by October 31.

--Ray