or following a POSIX class
or preceeding a POSIX class
or following ^ if the ^ is the first character
etc

Basically, anywhere it doesn't make sense to treat it as a range seperator.

Escaping - (like the OP needlessly did for ( and )) will force it to match literally.

In reply to Re^3: Order of terms in square braces by ikegami
in thread Order of terms in square braces by throop

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