@Wait
From SphereWiki
Added: @Wait trigger to skills (and @SkillWait to characters). This is called whenever Sphere wants to check if a character must wait before starting a skill. Normally this will be when a skill is selected from the skill menu (before @Select), but also when snooping a container or using a musical instrument.
ARGN1 = the skill the character is attempting
ARGN2 = the skill that is currently being used
RETURN 0 = The character can start the other skill (bypasses default checks)
RETURN 1 = The character must wait (bypasses default checks)
RETURN 2 = Perform default checks