*Description* Sort graphs are graphs that represent the dependencies between sorts in a grammar. *Visual clues* The following example sort graph provides a legend for the interpretation of sort graphs: http://www.cwi.nl/~jvisser/incomplete.sdf.sg.gif It was generated from http://www.cwi.nl/~jvisser/incomplete.sdf. In other words: _Bottom sorts_: Dotted outline _Nondeclared top sorts_: Dashed outline _Declared sorts_: Box shape _Declared top sorts_: Bold outline, box shape _Nondeclared sorts_: Eliptic shape *Terminology* _Sort_: In SDF grammars, non-terminals are called sorts. _Used sort_: A sort that occurs in the left-hand side of an SDF production. _Defined sort_: A sort that occurs in the right-hand side of and SDF production. _Declared sort_: A sort that occurs in a *sorts* section. _Bottom sort_: A sort that has been used but not defined. _Top sort_: A sort that has been defined, but not used. *See also* getsortgraphGT