About reading the mixer`s port-to-port isolation

Hello,
when reading the RF-LO ports` isolation, which frequency should i read at ? RF or LO frequency? And the RF-IF , LO-IF ports?
Thank you!

Usually the LO leakage is unwanted, so regarding LO-RF and LO-IF, the datasheets are referred to LO frequency.

Different the case of RF-IF isolation, for downconverters the RF-IF isolation is given for RF frequencies.

Since mixer is not linear, mind that isolations may change a lot vs LO level.