3.5. Sequence Group section says
Elements enclosed in parentheses are treated as a single element, whose contents are strictly ordered. Thus,
elem (foo / bar) blat
matches
(elem foo blat)
or(elem bar blat)
, and
Given exactly one element is allowed what exact payload does the "strictly ordered" part carry?
The sequence group (a b c)
is just for grouping the given elements. This is used for repetitions
like
*(a b c)
The entries inside the sequence group must appear in the given order. Then the sequence group itself can appear/match based on other operators (like the *
operator above).
The example shown in 3.5 Sequence Group is only for shown the issue between
elem (foo / bar) blat
and
elem foo / bar blat
that the ()
is needed when you want a matching of elem foo blat
or elem bar blat
.