Rudy's OBTF

In-pattern recursive item

A component of the pattern:

@startebnf
!theme plain
RECURSIVE-ITEM = {RECURSIVE-ITEM}- | "(", {RECURSIVE-ITEM}, ")" | ITEM;
@endebnf

where	`(RECURSIVE-ITEM)`	captures the content of `RECURSIVE-ITEM`,
	`()`	captures the position of `(`, and
	`ITEM`	is the item.