This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)


is a short string that identifies the type of computer system on which Mathematica is being run.
  • Computer systems with the same $SystemID should be binary compatible, so that the same external programs and .mx files can be used.
  • Sometimes binary compatibility may only be complete when the same version of the operating system is used.
  • Values for $SystemID contain only alphanumeric characters and dashes.
  • Typical values are , , and .
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