As part of the definition of the previous version of the High Performance Fortran language, HPF 1.1, a subset language was formally defined, based on the Fortran 77 language. The goal was to permit more rapid implementations of a useful subset of HPF that did not require full implementation of the new ANSI/ISO standard Fortran (``Fortran 90'').

No subset language is defined as part of the current version, HPF 2.0. This Annex is included in the HPF 2.0 language document as a convenient summary of the HPF 1.1 Subset, which has served as a minimum requirement for HPF implementations.

- Fortran 90 Features in the HPF 1.1 Subset
- HPF 1.1 Directives and Language Extensions in the HPF 1.1 Subset