So many subfields to choose from. When in doubt, consult your authority control librarian. You bet there is.
Subsequent editions provide even more guidance with explicit subfield coding.
In addition, LC has begun to distribute subdivision authority records that provide subfield data in 18X fields and citations to free-floating subdivision lists in 073 fields. That s reassuring. In a small number of cases, dizziness and nausea may occur, especially if retrospective conversion is contemplated. Operation of heavy machinery is not advised. As the label states, use only when it represents what the item cataloged actually is.