The BLAS library is used by Macaulay2 for its linear algebra routines. It is available at http://www.netlib.org/blas/.
The source of this document is in /__w/M2/M2/macaulay2-1.26.05+ds/M2/Macaulay2/packages/Macaulay2Doc/ov_preface.m2:206:0.