It's just the vmt that matters far as I know.
I have models using the same specular map but different vtfs that aren't remotely named the same, for example.
And a vmt without a texture reference (or an incorrect one) just gives the purple checks in the texture browser. A vtf with no vmt is skipped by the material browser.
So I'd say the naming conventions for vtfs are just that, naming conventions. It obviously does make sorting which vtfs belong to which vmts easier, but it's not necessary to my knowledge.
Kep
I have models using the same specular map but different vtfs that aren't remotely named the same, for example.
And a vmt without a texture reference (or an incorrect one) just gives the purple checks in the texture browser. A vtf with no vmt is skipped by the material browser.
So I'd say the naming conventions for vtfs are just that, naming conventions. It obviously does make sorting which vtfs belong to which vmts easier, but it's not necessary to my knowledge.
Kep