Update to audit_conform in new core_cif

[James Hester]

Dear Core CIF DMG,

Please see the small adjustment to DDLm core_cif proposed below. As this
has arisen from discussions in the DDLm group, they are also included in
this mailing (apologies to those of you who see this twice).  If you
disagree
with this change, please initiate discussion within one week.

James.
=====================================================

Explanation
=========

The recently circulated draft of cif_core defines the audit_conform
category to be of type 'Set', which means only single values of its
datanames may be present in a datablock. This would mean that only a
single dictionary could be specified as a reference for the datanames
in the datablock.  DDLm provides an 'import' mechanism that allows
dictionaries to build on each other (for example, pd_CIF could
'import' cif_core). While this mechanism covers some cases, it is
impractical to expect a separate dictionary to be created and
distributed for every combination of component dictionaries: for
example, there would need to be distinct separate dictionaries for
powder + magnetism, powder + incommensurate, magnetism +
incommensurate and so forth.

The following change simply returns audit_conform to its 'Loop'
status. Note, however, that the notional 'merging' behaviour of
dictionaries from the old cif_core is not carried over.  Given that
few applications (alas) use this category, and fewer if any actually
rely on non-trivial merging behaviour, this is not expected to be an
issue.

See the text of the category definition below for a precise
description of how multiple dictionaries should be combined. Note that
duplicate definitions are allowed and likely, for example, if both
dictionaries internally import cif_core.  This also means that
including dictionaries that are already internally imported in one or more
of
the listed dictionaries is not an error.

James

==================

save_AUDIT_CONFORM

_definition.id                          AUDIT_CONFORM
_definition.scope                       Category
_definition.class                       Loop   #Changed
_definition.update                      2016-06-17 #Changed
_description.text                       # Changed
;
     The CATEGORY of data items used describe dictionaries and
     dictionary versions to which data names in the current data block
     are conformant.  When multiple dictionaries are listed, a
     notional overall dictionary is obtained by assuming that each of
     the listed dictionaries is imported in 'Full' mode within the
     notional dictionary's 'Head' category, ignoring duplicate
     definitions.
;
_name.category_id                       AUDIT
_name.object_id                         AUDIT_CONFORM
_category.key_id                        '_audit_conform.dict_name'  #Added

save_



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