NOTE: This section will be extended by a future fascicle.

Variables and objects implicitly refer to locations or sequences of locations. A vector, for example, contains as many locations as there are elements in the vector. A new value may be stored into one of these locations using the vector-set! procedure, but the vector contains the same locations as before.

An object fetched from a location, by a variable access or by a procedure such as car, vector-ref, or string-ref, is equivalent in the sense of eqv? to the object last stored in the location before the fetch.

Every location is marked to show whether it is in use. No variable or object ever refers to a location that is not in use. Whenever this report speaks of storage being allocated for a variable or object, what is meant is that an appropriate number of locations are chosen from the set of locations that are not in use, and the chosen locations are marked to indicate that they are now in use before the variable or object is made to refer to them.