Is the 3(b) exemption in a by-law valid when the exemption is in the form of an area exemption?

In my view, Kehler v. Surrey, supra, does not support the City's submission that there is no reason to find the 3(b) exemption invalid when the exemption is in the form of an area exemption and the exemption "designates an area". It is the underlying purpose and not merely its form that is determina­tive of a by-law's validity. The City must exercise its powers in accordance with the purpose for which the powers are granted. For that reason, simply inquiring into whether the distinction in the by-law is defined by area and is therefore in the requisite form will not be sufficient to uphold the by-law.