The following notations are used in describing grammars and languages:
| V | a string of 0 or more elements |
| from the set V | |
| V+ | 1 or more elements from V |
| V? | 0 or 1 elements from V ( i.e., optional) |
| a | b | either a or b |
| < nt> | a nonterminal symbol or phrase name |
| &epsilon | the empty string |
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