Semantic properties are domain-specific specification constructs used to augment an existing language with richer semantics. These properties are taken advantage of in system analysis, design, implementation, testing, and maintenance through the use of documentation and source-code transformation tools. Semantic properties are themselves specified at two levels: loosely with precise natural language, and formally within the problem domain. The refinement relationships between these specification levels, as well as between a semantic property's use and its realization in program code via tools, is specified with a new formal method for reuse called kind theory.