I am currently working on a project and I'm about to get the Gerber files checked by FreeDFM.com. My question is, in my Gerber files, there are a couple that have the extension .C1 and .C2. In FreeDFM.com they want me to specify what these are (Inner copper layers, top layers etc.), but I have no idea what they are.
Any help in determining what these are would be very much appreciated!
Normally the mid-layers in Altium are .G1, .G2, etc. Top and bottom layers are .GTL and .GBL respectively.
Possibly you're mistaking the G for a C, or possibly the program could be configured to use those extensions (though I don't think the version of Altium we're using has that capability).
I ran into this also this morning - turned out to be the export from camtastic to gerber setting "Separate Composite layers to individual files" checkbox. It should NOT be checked.