Instructions can be given in any form (spoken live, written, recorded, projected etc) to performer(s) or participating audience who, acting upon them, embody the work at the same time as experiencing it. The outcome will often have a degree of indeterminacy.
The action can be performed alone, or together with others who may or may not receive the same set of instructions. The actions can be viewed with or without audience outside of the instruction-giving situation. It can happen in any number of possible places / spaces.
Sometimes instructions are only meant to be read or listened to, the result of acting upon them left to your own imagination, in turn potentially enhancing one’s perceptual sensitivity. Perhaps useful to remember: being given an instruction, being told to do something - this of course is real, and it has an effect, regardless of whether or not you carry it out.