Manipulates metaproperties. When turned on, A linked objects have a metaproperty added, and R linked objects have a metaproperty removed. The metaproperty can be named with @code (the code is any identifier that is convenient for you) and a Scode link will point to the metaproperty. Or just name the metaproperty directly:
aFrobInert. Turning off the trap removes A from links and adds to R links.