There are some differences among the various BLAS interfaces available, especially ACML and the rest. If you ever need to work with multiple BLAS libraries, TRUST ME THIS WILL SAVE YOUR LIFE.

Specifically there are usage notes for Intel Math Kernel Library(MKL), AMD Core Math Library (ACML), Cray's Scientific libraries (xt-libsci), GotoBLAS and IBM's ESSL libaries.