An optional label.

A line-start delimiter. The standard defines the line-start delimiter as a space (<SP>) character. In order to enhance routine readability, GT.M extends M by accepting one or more tab (<HT>) characters as line-start delimiters.

Zero or more level indicators, which are periods (.). The level indicators show the level of nesting for argumentless DO commands: the more periods, the deeper the nesting. M ignores lines that contain level indicators unless they directly follow an argumentless DO command with a matching level of nesting.

For more information on the DO command, refer to the "Commands" chapter in this manual.

Zero or more commands and their arguments. M accepts multiple commands on a line. The argument(s) of one command are separated from the next command by a command-start delimiter, consisting of one or more spaces (<SP>).

A terminating end-of-line, which is a carriage return, line feed (<CR><LF>) sequence.