020-12 Wyo. Code R. § 12-3
The design and construction standards included in these regulations are directed toward conventional public water systems. These standards impose limiting values of design for which a construction, installation, or modification permit application and plans and specifications can be evaluated by the division.
The terms "shall" and "must" are used when practice is sufficiently standardized to permit specific delineation of requirements or when safeguarding public health or protection of water quality justifies such definite action. Other terms, such as "should", "recommend", and "preferred" indicate desirable procedures or methods which allow deviations provided the purpose of these regulations can be accomplished.
The applicant shall use the date referenced copy of other standards referred to in these regulations. Where no date is listed for the referenced standards, the standards used shall be those in effect when these regulations become effective.
020-12 Wyo. Code R. § 12-3