The pound sign (#) is the comment character. Any text on a line after a pound sign is not interpreted by format.
Each definition in the format.dat file appears on a single logical line. If the definition is more than one line long, all but the last line of the definition must end with a backslash (\).
A definition consists of a series of assignments that have an identifier on the left side and one or more values on the right side. The assignment operator is the equal sign (=). The assignments within a definition must be separated by a colon (:).
White space is ignored by format. If you want an assigned value to contain white space, enclose the entire value in double quotes ("). This will cause the white space within the quotes to be preserved as part of the assignment value.
Some assignments can have multiple values on the right hand side. Separate values by a comma.