What is the unit of time_lock_delta in LND? LND has a configuration setting called time_lock_delta with the description "The required timelock delta for HTLCs forwarded over the channel.". I assume this to refer to some measure of time, but what is the unit of this value?



None of the four files in the LND repository that contain this string appear to mention the unit either.
The time_lock_delta is the minimum difference in the number of blocks between the CLTV of an incoming HTLC and the forwarded HTLC.

Full details are described in BOLT2 # CLTV expiry delta.