Source: BL Guide
BL practice: Use LCSH terms in 374, for purposes of retrieval, machine matching and linked data.
The purpose of 100 ‡c is slightly different, being to create an access point that is both unique and informative to the user.
An LCSH term will almost always need adapting before it can be used in 100 ‡c. LCSH terms for classes of persons are given in the plural, whereas an addition to a name access point should be in the singular:
|100||1||Smith, John ‡c (Librarian)|
|374||Librarians ‡2 lcsh|
An LCSH term may be too narrow or broad, and a broader or narrower free-text term may be better for 100 ‡c:
|100||1||Jackson, Richard ‡c (Motion picture producer)|
|374||Motion picture producers and directors ‡2 lcsh|
An LCSH term may have a qualifier that is not appropriate in 100‡c:
|100||1||Roberts, Susan (Soprano)|
|374||Sopranos (Singers) ‡2 lcsh|
Sometimes, a free text term will be preferable to its LCSH equivalent:
|100||1||Jones, Peter ‡c (University lecturer)|
|374||College teachers ‡2 lcsh|