Rule and subrule options

option	description
`k`	Specify the exact lookahead to be used by the subrule.
`greedy`	Valid values are `true` and `false`. Default is `true`. Normally symbols are matched greedily so that if a symbol can be matched immediately or by exiting the subrule the parser chooses to match the symbol immediately.
`backtrack`	Rule-specific version of the `backtrack` grammar option. See Grammar options for details.
`memoize`	Rule-specific version of the `memoize` grammar option. See Grammar options for details.