Swapping codes in post processor

[hatcat]

Hi all,
I've been fiddling with CamBam for a short while to generate code for my 20 yr old ANCA controller. All is going pretty well, but there is one question I have. In the post processor, there is a {$units} command which inserts the G code for imperial (G20) or metric (G21) as appropriate. My problem is that the controller doesn't like these codes as it uses G70/G71 for units.

I can fix the controller errors by removing the {$units} command from the .cbpp and this is not a big problem as I mostly use the one unit system (metric) anyway, but I just know I am going to get caught one day when I do a through hole printed circuit board which will be imperial!

Is there an easy way to get G70/G71 instead of G20/G21 for imperial/metric? I thought that the <G0>G0</G0> trick might have worked for me (using <G21>G71</G21>), but alas, no. Perhaps this could be extended to handle other codes? Thanks and any help appreciated.

Peter