A fixed, purposeful means to make a character Restrained in place: Bound Wrists, Fixed Restraints, Handcuffs, etc. The restraints can be on a character, or it can be implied that they will be used to restrain a character.
Characters that are Held Down are restrained, but they are not considered in restraints. Likewise, characters that are stuck may be restrained in their movements, but unless they were purposefully stuck there, they aren't in restraints.