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The term 'object' covers both the beneficiaries and potential beneficiaries of a trust. Where a trustee is accorded a discretionary power over the allocation of the trust's benefits, some of the trust's designated objects may not emerge as full-fledged beneficiaries, as they may find themselves excluded from the trustee's selected pattern of distribution.

Generally speaking, for a trust (other than a charitable trust) to be valid, it must provide a sufficient measure of certainty in relation to its objects. It's objects must, in other words, be judged suitably ascertainable. For a discretionary trust, this means that its class of objects must be described in terms that are precise enough to say whether any given individual either 'is or is not' a member of that class (McPhail v Doulton (1971)).

The implications of Lord Wilberforce's famous 'is or is not' test are in this context quite clear: (i) the identity of even a potential beneficiary must (in principle) be determinable; (ii) although a potential beneficiary may not (as yet) possess any concrete rights in relation to the trust's benefits, he at least has the right to be considered for selection to this status.

See also beneficiary, certainty of objects, McPhail v Doulton (1971).