A question came up during implementation w.r.t. GT texture name for base and subordinate model textures (such as light map, material etc..).
CDB spec (in version 3.2 section 3.4.6 but this applies to CDB 3.0 as well) provides an example as follow:
Is it mandatory that the texture and material have the same file name with only the extension changing.
No, it is not mandatory but remains good practice as it will keep the files in the same folder. A CDB reader application, for GT models, is required to open the 3D model (OpenFlight) and use the texture palette file references in order to find all textures. This reference includes the full file name sufficient to load the right files.
Note that the file name prefix with dataset (Dnnn_Snnn_Tnnn) is the way to identify the nature of the texture (base vs subordinate lightmap, normal map etc...) as well as material texture (in spec 3.2).
However, there are two cases where the file name is imposed.
1 - Skin textures must have the same name as the base texture (with different Snnn_Tnnn) fields.
2 - CMT file must have the same name as the material texture (tiff file)
Please respond if further details are required.