What is the legal test for a hybrid term?

Of the authorities cited by my colleagues, only one explicitly contemplates a hybrid term based on a distinction between a stated perpetual term and a shorter stated term that is perpetual in effect. In Neale v. Katz, [1979] C.A. 192, Mayrand J.A. distinguished in obiter between a lease with a perpetual term — that is, a stated term of forever — and a lease that has a lesser fixed term but assumes a perpetual character for only one of the parties by operation of a renewal clause (p. 194). In support of that distinction, however, Mayrand J.A. relied on two common law authorities as well as a strained reading of French academic commentary. I would therefore decline to adopt his reasoning.