http://www.ada-auth.org/standards/22rm/html/RM-1-1-4.html http://www.ada-auth.org/standards/22rm/html/RM-1-1-4.html The Ada Reference Manual specifies the nota

http://www.ada-auth.org/standards/22rm/html/RM-1-1-4.html http://www.ada-auth.org/standards/22rm/html/RM-1-1-4.html The Ada Reference Manual specifies the notation they use. They're using a variant of Backus-Naur Form and they describe their particular variant in the section I linked above.