Trigger workflow in classic Tomb Raiders

Antitriggering of pre-activated entities since TR3

In TR3, antitrigger behaviour was slightly changed for pre-activated entities (that ones with pre-set activation mask). When in TR1-2 antitrigger had no effect on such entities, in TR3-5 it was possible to antitrigger pre-activated entity, just like ordinary one.

Most likely, the change was either not resetting event flag on pre-activation or ignoring it completely on antitriggering.

Ability to activate one-shot triggers more than once in TR1

In TR1, one shot flag meaning was different from later versions. For example, while in TR2-5 one shot flag blocked switch entity from further usage, in TR1 it was possible to use it indefinately.