Changes for Zthes profile, version 0.3b

Changes between versions 0.2 and 0.3b:

• Add the ``changes'' section.
• Note the author's change of affiliation and email address.
• Add postings sub-record.
• Change termType representation of Preferred Term from ``NT'' to ``PT'' (to avoid confusion with ``NT'', meaning Narrower Term).
• Remove the ``TT'' value of termType (which is redundant, since it's always true when there are no ``BT'' relations.)
• Add multilingual support, in the form of the new ``LE'' value of the relationType element.
• Add thesAdmin access point, used to find records which are considered suitable starting points for browsing, and to find whole-thesaurus information.
• Add the relatedTermID access point, used to find all the records related to a specified one in a specified way.
• Specify the OIDs of objects defined in this profile.
• Remove sourceDb, createdBy and modifiedBy from tagSet-Zthes: equivalents are being added to tagSet-M and/or tagSet-G; the schema now uses these new generic elements in place of the old tagSet-Zthes ones.
• Remove createdBy and modifiedBy from the Zthes-1 attribute set: equivalents are being added to the utility and/or cross-domain attribute sets; searching now uses these new generic access points, together with appropriate functional qualifiers, in place of the old Zthes-1 ones.
• Some utility attribute-set access points have been renumbered and/or renamed: this version of the Zthes profile uses the new numbers and names.
• Add section 3.7 about Explain (contributed by Denis Lynch).
• Add the use of Scan to the section on future directions.
• Remove lightweight support for non-preferred terms, use of the Z39.50 date/time structure and alternative representation of relationType from the section on future directions.
• Update the reference to the utility attribute set.
• Update Appendix C to describe current implementations, including URLs to running systems.
• Add Appendix D to describe current applications.
• Minor editorial changes and corrections.