Editing Backus–Naur form (section)

=== EBNF ===
{{Main|Extended Backus–Naur form}}
There are many variants and extensions of BNF, generally either for the sake of simplicity and succinctness, or to adapt it to a specific application. One common feature of many variants is the use of [[regular expression]] repetition operators such as <code>*</code> and <code>+</code>. The [[extended Backus–Naur form]] (EBNF) is a common one.

Another common extension is the use of square brackets around optional items. Although not present in the original ALGOL 60 report (instead introduced a few years later in [[International Business Machines|IBM]]'s [[PL/I]] definition), the notation is now universally recognised.