.GBL – Gerber Bottom Layer
.GTL – Gerber Top Layer
.GBS – Gerber Bottom Solder Resist
.GTS – Gerber Top Solder Resist
.GBO – Gerber Bottom Overlay
.GTO – Gerber Top Overlay
.GBP – Gerber Bottom Paste
.GTP – Gerber Top Paste
.GKO – Gerber Keep-Out Layer
.GM1 – Gerber Mechanical 1
.GM2 – Gerber Mechanical 2
.GPT – Gerber Top Pad Master
.GPB – Gerber Bottom Pad Master