Multiple Sort Keys

Issue raised by: CA Sanders zzaascs@cs6400.mcc.ac.uk Wed, 17 Dec 1997 12:19:45 +0000

In the SortRequest, sortSequence is defined as a SEQUENCE OF SortKeySpec, with the comment "order of occurrence is from major to minor". If it is desired to sort on Author and then Title, should there be two occurrences of SortKeySpec, the first containing Author, the second Title, or may both be combined into a single SortKeySpec?

If there should be separate instances of sortKeySpec, why may each SortKeySpec contain multiple attributes?

If it is desired to sort on Author and then Title, there should be separate occurrences of SortKeySpec, for Author, and Title; they should not be combined into a single SortKeySpec. The fact, as noted, that sortSequence is defined as "... SEQUENCE OF SortKeySpec" with the associated comment "-- order of occurrence is from major to minor" impies that separate instances of SortKeySpec is intended for each sort key.

The reason that SortKeySpec may include multiple attributes is for generality. When SortKey assumes the CHOICE sortAttributes, it's purpose is to specify a search field, and though in bib-1 that's done with a single Use attribute, the Sort definition avoids assuming that bib-1 will necessarily be the attribute set.