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6.7 The Symbol Table

Every symbol used in a grammar has to be defined at least once in the symbol table. Every symbol must be followed by a semicolon: verb; noun; adjective;

Symbols that are being defined that way are called atoms. A symbol can also be defined as a molecule. Then the entry for this symbol has the following format:

     symbol := list;

The list for this symbol must consist of at least two atoms; no atom may occur more than once in the list. This list will be used by the operators ~ and /~, atoms, and multi. The lists in the symbol table must be different from each other; it does not suffice that they only differ in the order of their elements. If a symbol is defined more than once in the symbol table, the definitions must all match: Either the symbol must always be defined atomic or it must always be molecular with the same atom-list.