How to Read BNF Diagrams

The MaxL grammar is represented using Backus-Naur Form (BNF) syntax notation. Keywords, represented in plain, lower-case font, are to be entered literally. Terminals, represented in upper-case without brackets, are to be replaced by values in the appropriate format defined in the Terminals table. Non-terminals, represented in upper-case with angle brackets <>, are further defined in other diagrams. Keywords and variables on the main line are required; optional grammar is recessed. A vertical stack of words represents alternatives. Bold words indicate defaults when no word is chosen.

Diagrammatic Symbols

	Statement begins here.
	Statement continues on next line.
	Statement is continued from previous line.
	Statement ends here.
	Alternatives: optionally select one keyword. Boldface indicates default if no selection is made.
	Alternatives: selection of one keyword is required.
	A comma-separated list of any length is permitted.
	Word is not further defined. Replace with value of format shown in the Terminals table.
	Word used in statement is further defined.
	Non-terminal used in statements is defined here.

Sample BNF Diagram

The following diagram illustrates a variant grammar which could be used to parse the following English sentence:
"The quick brown fox jumps over the lazy dog."

Valid sentences parsable by this grammar:

The fox jumps over the dog.
Bold letters indicate a default value when no option is entered; therefore, entry of this statement would be interpreted as The brown fox jumps over the dog.
The quick brown fox jumps over the dog.
The red fox jumps over the lazy cat.
The quick brown fox jumps onto the tired elephant.