The file is free-formatted, integers, reals and additional keywords are entered following the directive on each record. Real and integer numbers must be separated by a non-numeric character (preferably a space or comma) to be correctly interpreted. No logical variables appear in the control file. Comment records (beginning with a #) and blank lines may be added to aid legibility (see example above). Additional annotation may be added onto the directive line, provided it does not contain numerical characters, or appear where a directive or keyword is expected. The CONTROL file is not case sensitive.
Between the header and the finish directive, a wide choice of control directives may be inserted. These are described below.