Trying things like 650 0 or 650?0 doesn't work; I keep getting all of the 650s, not limited to the LCSH. If I ask for one column with 650 0 and one with 650 2, both exports are identical.
According to the Sierra Manual, however, the functionality is there:
Note that you can export specific MARC fields and subfields by entering the "!" character in the Field box. Enter your MARC field criteria (including indicators and subfields if desired) in the same format used for MARC field searching when creating a review file.
And under field searching, it specifies:
If you choose ! MARC Tag, the system provides a prompt indicating what to enter:
MARC TAG tttii|ssss
ttt 3 numbers for the MARC tag
ii up to 2 numbers or spaces for the indicators (optional)
|ssss up to 4 subfields indicated by the '|' (optional)
However, I can't find an example or figure out how to actually do it. Any thoughts or tips?