more fun with vW grammar

[Jose E. Marchesi]

> as I am trying to make the a68 metanotion grammar LL(1))-parseable,
> I found a probable error in the revised report.
>
> The metanotion COMMON has as alternative MODE FIELDS {411A}
> but FIELD :: MODE field TAG. has a mode attached already.
> COMMON is used only in declaration and joined-definition.
>
> where is the error?

Hm.

 COMMON :: MODE FIELDS.
 FIELDS :: FIELD; FIELDS FIELD.
 FIELD :: MODE field TAG.

I don't see any connection between the MODE in FIELD and the MODE in
COMMON.  The terminal metaproduction of COMMON in an hyperrule is
produced by applying simple substitutes, one after the other.

On the other hand, as expected the `MODE FIELDS' meta-alternative is
only used in joined definitions.  Substituting it in 4.1a would lead to
a blind alley as far as I can see.

So where is the error? :)