Only the simplest version of FORALL statement is required in the subset. Note that the omission of the PURE attribute from the subset means that only HPF and Fortran 90 intrinsic functions can be called from the FORALL statement. No other subprograms can be called.
Only the intrinsics which are useful for declaration of variables and
mapping inquiries are included in the subset. The full set of
extended operations proposed for the HPF library is not required and
since MODULE is not part of the subset, the HPF_LIBRARY module
is also not part of the subset. The extrinsic interface attribute is
also not in the subset. This includes any specific extrinsic models
such as the model described in the Annex
All of these HPF language reductions are made in the spirit of
allowing vendors to produce a usable subset version of HPF quickly so
that initial experimentation with the language can begin. This list of
HPF features excluded from the subset should not be interpreted as
requiring implementors to omit the features from the subset.
Implementations with as many HPF features as possible are encouraged.
The list does, however, establish the features a user should avoid if
an HPF application is expected to be moved between different HPF subset
implementations.
(End of rationale.) 
.