What are the rules of interpretation in the interpretation of tax legislation?

And further, at page 20: … The rules formulated in the preceding pages, some of which were relied on recently in Symes v. Canada, 1993 CanLII 55 (SCC), [1993] 4 S.C.R. 695, may be summarized as follows: - The interpretation of tax legislation should follow the ordinary rules of interpretation; - A legislative provision should be given a strict or liberal interpretation depending on the purpose underlying it, and that purpose must be identified in light of the context of the statute, its objective and the legislative intent: this is the teleological approach; - The teleological approach will favour the taxpayer or the tax department depending solely on the legislative provision in question, and not on the existence of predetermined presumptions; - Substance should be given precedence over form to the extent that this is consistent with the wording and objective of the statute; - Only a reasonable doubt, not resolved by the ordinary rules of interpretation, will be settled by recourse to the residual presumption in favour of the taxpayer. …