This Supplement comprises three sets of changes. The most extensive changes, in Clauses 6, 7, and 27, make this Standard consistent with the National Building Code of Canada (NBCC), 2005. For load combinations, the 2005 NBCC uses the companion action approach. In addition, a uniform approach to qualify the importance of the structure for different load effects has been adopted. Clause 27, Seismic Design Requirements, has been reproduced in its entirety and has been revised to agree with Section 4.1.8 of the NBCC, entitled Earthquake Loads and Effects The revisions to Clauses 6, 7, and 27 have necessitated other minor changes to information such as definitions and symbols.