Select the Miscellaneous tab of the Options (Settings menu) command to display these parameters:

Configuration File Specifies an optional task (*.blc file) that is automatically executed within the Editor for NC programs nominated for this control. This task converts the NC code of the current line into readable text, which is displayed in the Editors status bar.
Click on the Browse button to search for a configuration file. This displays configuration files with the extension .blc.
Comment From This parameter defines the start of a comment line in the NC file for this Machine, which would typically be the ( character.
To This defines the end of a comment within the NC file for this Machine, and would typically be the ) character.
The colour of comment lines can be controlled from the Editor tab. Comment lines are sent to the machine tool.
Optional Line This defines the character that appears in front of the sequence number. This is typically the / character, and indicates to the Machine that any block of information preceded by this character may be ignored if the Machine is in that particular mode.
Set Units The information entered here is used by the Format (Edit menu) command.
Metric Indicates the code and value that defines that the machine is to operate in metric mode. For an ISO type control this is typically G21.
Imperial Indicates the code and value that defines that the machine is to operate in imperial mode. For an ISO type control this is typically G20.