The title is composed of two subjects that frequently appear in the discussion about the periodic heating method. The former part of the title means the minimum knowledge required to use the periodic heating method. Meaning of the latter part is clear but it should be noted that for development in future advantage of the periodic heating method has to be understood correctly by many researchers. The advantage will be explained by suitable authors in the following papers. In this short paper a few things considered to belong to the periodic heating method minimum are described.