In this section, the support of functions is defined and corresponding theorems are provided. Since basic properties (see suppval) are based on the Axiom of Union (usage of dmexg), these definition and theorems cannot be provided earlier. Until April 2019, the support of a function was represented by the expression (see suppimacnv). The theorems which are based on this representation and which are provided in previous sections could be moved into this section to have all related theorems in one section, although they do not depend on the Axiom of Union. This was possible because they are not used before. The current theorems differ from the original ones by requiring that the classes representing the "function" (or its "domain") and the "zero element" are sets. Actually, this does not cause any problem (until now).