Example

Suppose the user has his additive model routine in the file USER1.FOR in USRDISK:[RONTGEN.XSPEC].

$ set def usrdisk:[rontgen.xspec]     !  Change directory.

$ fortran user1                       !  Compile.

$ mkumd user1                         !  Link the executable.

$ setumd user1                        !  Set logical umdshr.

$ xspec                               !  Start xspec.

XSPEC> model wabs useradd1         !  Define model.