Authority headings can be used in more than one context

[Srey Seng]

Currently, linking in Evergreen works or is configured in such a way that an auth's 151 tag would control, for instance, a bib's 651 tag, and an auth tag 110 would control, for instance, a bib tag 710. Similarily, a bib tag 651 would link to an auth tag 151, and likewise a bib tag 710 would link to an auth tag 110.

However, it appears that an authority heading can be used in more than one context and can control wider range of bib tags than the strict confines of, for example, an auth's 151 (Geographic name subject) controlling a bib's 651 tag (Subject Added Entry - Geographic Name)

A concrete example:

Bib D:
=710 1\$aBarnstable County (Mass.)

Auth D:
=151 \\$aBarnstable County (Mass.)

Auth D can be used in both a "subject" and a "name" context, and should control Bib D but it does not in current linking.

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additional background:
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According to a mailing list conversation, authority records "have coding in the fixed fields to show how the headings can be used".

Also, someone at LC gave the following explanation in response to my inquiry** regarding a specific scenario: 'There is only 1 authorized place and only 1 authority for it, Barnstable County (Mass.). When used to represent the "corporateness" of the place, such as when talking about the government in that place, the X10 field is used. When used to describe the place as a subject, such as in travel books describing the place, poetry by authors of that place, etc., the 651 is used.'

**Extracted inquiry:
There are two bib records, as shown in the example below. Bib A has a 710 with the text Barnstable County (Mass.). Bib B has a 651 with the text Barnstable County (Mass.). However, searching for authority record only revealed a Barnstable County (Mass.) with Geographic as the type of authority record.

Bib A: http://lccn.loc.gov/86101942
710 1_ |a Barnstable County (Mass.)

Bib B: http://lccn.loc.gov/11030227
651 _0 |a Barnstable County (Mass.)

But there appears to be only one authority record:
Auth A: http://id.loc.gov/authorities/names/n83003661
=151 \\$aBarnstable County (Mass.)

My question: In an authority control environment, which bib does Auth A controls? Does Auth A control Bib A (with the 710 tag), or does it control Bib B (with the 651 tag)?...Or both?
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