_std/macros/items.dm

isitem	Returns true if the given x is an item.
isgrab	Returns true if the given x is a grab (obj/item/grab)
equipped_or_holding	Returns true if x is equipped or inside & usable in what's equipped (currently only applicable to magtractors)
IS_WORN_BY_SOMEONE_OTHER_THAN	Returns TRUE if item is worn by a human other than `user`, FALSE otherwise

Define Details

Returns TRUE if item is worn by a human other than user, FALSE otherwise

Returns true if x is equipped or inside & usable in what's equipped (currently only applicable to magtractors)

Returns true if the given x is a grab (obj/item/grab)

Returns true if the given x is an item.