I understand why you would think so, as I haven't heard the usage anywhere else in the software world that I've been, but it is a standard usage in that community; it's not hard to find examples [0] [1] [2] [3].

[0] http://people.sc.fsu.edu/~jburkardt/f_src/f_src.html

[1] http://www.unige.ch/~hairer/software.html

[2] http://www.mcs.anl.gov/project/openadf-automatic-differentia...

[3] http://math.berkeley.edu/~strain/Codes/