Gonthier J.:-The issue in this case is whether the appellant, an institu tion devoted to the welfare of elderly persons living under the poverty line, may benefit from the tax exemption provided for in subsection 204(14) of the Act respecting Municipal Taxation, R.S.Q., c. F-22.1 ("AMT") for all its facilities. There are two main questions: (1) What are the principles that should guide the courts in interpreting tax legislation?