Re: error-checking algorithm for the redefinition

> fields of RefPattern (of JTREX)
> -------------------------------
>
> combineMethod: (none/interleave/choice)
>     specifies what method is used to combine patterns.
>
> haveHead: boolean
>     true if this named pattern already has a "head".
>     a "head" is a <define> declaration without @combine.

Why do you need haveHead? Isn't haveHead true iff the ref is defined and
combineMethod="none"?

James