Integer values less than 500,000,000 are interpreted as absolute block height. Values greater than or equal to 500,000,000 are interpreted as an absolute Unix epoch timestamp. The Monero CLI wallet only supports values less than 500,000,000; Unix timestamps must be submitted via RPC or another custom software.
The integer value will be interpreted by the protocol as an ***absolute*** block height value or Unix epoch timestamp, not a relative value. Using an integer value less than the current block height or a Unix epoch timestamp less than the current Unix epoch timestamp makes no sense. For example, if you want the Monero transaction to unlock 100 blocks from now, add 100 to the current block height.
