Explanation:
An open specification is a document that provides detailed information about the requirements, features, and functionality of a particular product or system. It is typically used when multiple vendors or manufacturers are able to meet the specified requirements.

Physical properties required for building materials:
- An open specification does include the physical properties required for building materials. This includes information such as strength, durability, thermal conductivity, and density. These properties are important for ensuring that the materials used in construction meet the necessary standards and requirements.

Chemical properties required for building materials:
- An open specification also includes the chemical properties required for building materials. This includes information such as resistance to corrosion, fire resistance, and chemical stability. These properties are important for ensuring that the materials used in construction are safe and suitable for their intended applications.

Description of workmanship to be achieved:
- However, an open specification does not typically include a detailed description of the workmanship to be achieved. Workmanship refers to the quality of the construction or installation work, including factors such as accuracy, precision, and attention to detail. While the specification may outline certain requirements for workmanship, such as tolerances or finishing standards, it does not provide a comprehensive description of the specific techniques or methods to be used.

Precautionary measures or storing of the product:
- An open specification may include precautionary measures or instructions for storing the product. This is particularly important for certain materials that may have specific storage requirements, such as chemicals or perishable goods. These instructions ensure that the product remains in optimal condition until it is ready for use.

In conclusion, an open specification does not include a detailed description of the workmanship to be achieved. It does, however, include physical and chemical properties required for building materials and may also include precautionary measures or instructions for storing the product.