AFAIK, cct is a format of ATENA 2D (and SARA 2D) only, not supoported by ATENA 3D nor GiD. Why do you ask?

Hello, running an .inp file from GiD in ATENA 3D is not very effective (no monitors displayed, much slower compared to AtenaConsole), I would recommend to run the analysis in AtenaConsole and always import the last finished step into ATENA 3D for postprocessing.

When working with Egr 3D or Sci, you can easily see/modify the whole .inp file (unlike Egr 2D where you need to copy-past the part for each analysis step separately). If you like to check (or set) the mesh generation parameters in a text way, you can capture the t3d mesh generator commands from ATENA 3D (involves a trick of copying temporary files) and replace the generated elements in the .inp file by the mesh generation commands. However, this procedure only makes sense if you need to randomize the geometry or a similar rare situation.