http://linuxcnc.org/docs/html/gcode/gcode.html
If your looking to hack your G-code and it does not do what you are wanting then this link will help.
Extract
1. Conventions
Conventions used in this section
In the G code prototypes the hyphen (-) stands for a real value and (<>) denotes an optional item.
If L- is written in a prototype the - will often be referred to as the L number, and so on for any other letter.
In...
G-Code
If your looking to hack your G-code and it does not do what you are wanting then this link will help.
Extract
1. Conventions
Conventions used in this section
In the G code prototypes the hyphen (-) stands for a real value and (<>) denotes an optional item.
If L- is written in a prototype the - will often be referred to as the L number, and so on for any other letter.
In...
G-Code