Squared brackets are placed around optional elements.

Curly brackets are placed to enclose a list of alternatives. Elements within this list are considered exclusive and are separated by vertical bars.

Repeatable arguments will be followed by an asterisk, meaning 'zero or more repetitions' or by a plus sign, mening 'one or more repetitions'.

A symbol in bold face like this one means a terminal symbol, that is, a string that must be written exactly as it appears here. Apart of using bold face, if this manual is printed or displayed using colours, dark blue colour will be used for terminal symbols.

A symbol like this in italics means a non-terminal symbol (a category name). It must be replaced by a specific element of that cathegory. If colour is possible they will appear in green colour.