explicit-locking.html "key values" reference

[jian he <jian.universality@xxxxxxxxx>]

hi.

https://www.postgresql.org/docs/current/explicit-locking.html

FOR KEY SHARE
Behaves similarly to FOR SHARE, except that the lock is weaker: SELECT FOR UPDATE is blocked, but not SELECT FOR NO KEY UPDATE. A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values, but not other UPDATE, and neither does it prevent SELECT FOR NO KEY UPDATE, SELECT FOR SHARE, or SELECT FOR KEY SHARE.

A key-shared lock blocks other transactions from performing DELETE or any UPDATE that changes the key values

querya: select col1,col2,col3 from a for key share of a

Does "the key values" refer to these rows returned by the querya?

I still feel confused about "the key values".