1.1 本规范涵盖石膏、硫酸钙和两种结晶形式的水分子的混合物，其化学式近似为CaSO 4. ·2小时 2. O。 1.2 以英寸-磅单位或国际单位制（公制）表示的数值应单独视为标准。在文本中，国际单位显示在括号中。每个系统中规定的值应独立于其他系统使用。两个系统的值不得合并。 1.3 本规范的正文引用了提供解释材料的注释和脚注。 这些注释和脚注（不包括表和图中的注释和脚注）不应视为本规范的要求。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。

1.1 This specification covers gypsum, calcium sulfate combined with two molecules of water in crystalline form and having the approximate chemical formula CaSO 4 ·2H 2 O. 1.2 The values stated in either inch-pound units or SI (metric) are to be regarded separately as the standard. Within the text, the SI units are shown in brackets. The values stated in each system shall be used independently of the other. Values from the two systems shall not be combined. 1.3 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the specification. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.