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This is the fifth edition of CSA O141, Softwood lumber. It supersedes the previous editions published in 1991, 1970, 1965, and 1959.
1.1 This Standard specifies requirements pertaining to the quality and uniformity of softwood lumber manufactured in Canada and establishes the designation "Canadian Standard Lumber" for lumber that meets the requirements of this Standard (see Clause 4).
1.2 This Standard covers the following topics: (a) classification; (b) measurement; (c) standard sizes; (d) grading rules; (e) identification (grade stamps and certificates); and (f) accreditation board and grading agency responsibilities.
This Standard also includes detailed Annexes covering lumber terminology and lumber industry abbreviations.
1.3 This Standard does not cover trade practices, grades (other than grading rules and identification), the details of accreditation board and grading agency inspection procedures, or strength values.
1.4 Although this Standard applies to softwood lumber, it may be applied to hardwood lumber used in applications that ordinarily use softwood lumber.
1.5 In CSA Standards, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; "may" is used to express an option or that which is permissible within the limits of the standard; and "can" is used to express possibility or capability.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.
1.6 In keeping with the practice of lumber manufacturers throughout North America, sizes in this Standard are given in board measure units, which are expressed in yard/pound units (see Clause 6.1). Equivalent SI (metric) sizes, rounded to the nearest millimetre, are given in parentheses for the sake of convenience in use and in commercial transactions. The values given in yard/pound units are the standard. The values given in parentheses are for information only. See Annex E for a discussion of how metric dimensions have been calculated for this Standard.