Proper package relationships when a project depends on CBLAS

[Ghislain Vaillant <ghisvail@gmail.com>]

Dear all,

I have a package (ArrayFire), which build-depends on any 
C-implementation of BLAS.

At the moment, I am building against libopenblas-dev, but the latter is 
not available on all architectures and therefore restricts the build of 
the source package (ArrayFire) to the restricted set that provides it.

Since multiple BLAS-compatible implementation are available in the 
archive (BLAS, ATLAS, OpenBLAS...) and these can be switched from with 
the update-alternatives mechanism, I was wondering what the appropriate 
way should be to tell the Build-Depends and Recommends that it requires 
*one* of those implementation, and not OpenBLAS specifically.

I have looked on c.d.n, but nothing seemed like an obvious solution to me.

Many thanks for your help,
Ghislain