You are waiting at the end of the runway when tower says "Behind the landing Air Bus, line up and wait." In the United States you question the tower's sanity but under ICAO you are expected to acknowledge, repeating the clearance exactly, and as soon as you see the landing aircraft pass in front of you, you line up and wait. It is ICAO, to be sure, but I've only seen this done in Europe.
Everything here is from the references shown below, with a few comments in an alternate color.
[ICAO Doc 4444, ¶12.2.7] Conditional phrases, such as "behind landing aircraft" or "after departing aircraft", shall not be used for movements affecting the active runway(s), except when the aircraft or vehicles concerned are seen by the appropriate controller and pilot. In all cases a conditional clearance shall be given in the following order and consist of:
"SAS 941, BEHIND DC9 ON SHORT FINAL, LINE UP BEHIND".
Note.— This implies the need for the aircraft receiving the conditional clearance to identify the aircraft or vehicle causing the conditional clearance.
ICAO Doc 4444 - Air Traffic Management, 16th Edition, Procedures for Air Navigation Services, International Civil Aviation Organization, October 2016
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