Effectiveness of G-code

A block in the G-code contains all the executable G- and M-commands that are present in a common line. A line break signifies the end of a block.

A characteristic of most G-commands is that their instruction is retained for the subsequent blocks. They "take effect modally". For certain control commands, there are G-commands with an opposite instruction to reverse the original instruction. For instance, there is a modal command for activating path control operation (enable blending) and another modal command to deactivate path control operation (disable blending).

However, a characteristic of some G-commands is that their instruction becomes effective only for the current block. For the following blocks, the modal setting automatically takes effect again. They "take effect in blocks".