In other cases, you can import just the normals, and then generate the t/b, or you can generate all three.
Depending on which branch of mathematics you're using, one of either one of them is the properly defined term (and the other is nonsense).Why is that? The semantics in HLSL at least, are TANGENT and BINORMAL.
biTANGENT. Binormal is nonsensical in this context.
In computer graphics though, we use them interchangeably.