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Re: [ddlm-group] Adding a DDLm attribute for uniqueness

The troubling part of this is "unique within a loop".   The handling of relational keys is complex but clear, because
categories are well-defined.  The content of a loop beyond the relational model is not clear without much more information,
especially for numeric data and unicode data, both of which come with major ambiguities in terms of uniqueness.  The
situation gets even more confusing when trying to make a database from multiple entries.  We add keys precisely to allow for duplication
of existing keys.  How will we handle these new pseudo-keys?  I would suggest that any proposal be presented with
a clear view of how we will handle databases without breaking the new proposed constraints

On Thu, Jun 27, 2019 at 7:36 PM James Hester <jamesrhester@gmail.com> wrote:
Dear DDLm group,

A proposal has been put forward to enhance DDLm by the addition of an attribute that specifies that values of an item or group of items must be unique within a loop. This is something that was present in DDL1 and is absent in DDL2 and DDLm. The details of the proposal and some initial discussion are available at https://github.com/COMCIFS/cif_core/issues/119 .

Please provide your thoughts on this proposal.

best wishes,
James.
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