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  • f /: lhs = rhs assigns rhs to be the value of lhs, and associates the assignment with the symbol f.
  • TagSet defines upvalues or downvalues as appropriate.
  • The symbol f in f /: lhs = rhs must appear in lhs as the head of lhs, the head of the head, one of the elements of lhs, or the head of one of the elements.
  • A common case is f /: h [ f [ args ]] = rhs.
  • You can see all the rules associated with a particular symbol by typing ? symbol.
  • If f appears several times in lhs, then f /: lhs = rhs associates the assignment with each occurrence.
  • When it appears in symbolic form, TagSet is treated as a scoping construct (see Section A.3.8).
  • See the Mathematica book: Section 2.4.10Section A.5.2.
  • See also: Set, UpSet.