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The EXTRINSIC Prefix

H608 extrinsic-prefix	is EXTRINSIC ( extrinsic-spec )
H609 extrinsic-spec	is extrinsic-spec-arg-list or extrinsic-kind-keyword
H610 extrinsic-spec-arg	is language or model or external-name
H611 language	is [ LANGUAGE = ] scalar-char-initialization-expr
H612 model	is [ MODEL = ] scalar-char-initialization-expr
H613 external-name	is [ EXTERNAL_NAME = ] scalar-char-initialization-expr

• In an extrinsic-spec-arg-list, at least one of language, model, or external-name must be specified and none may be specified more than once.
• If language is specified without LANGUAGE=, language must be the first item in the extrinsic-spec-arg-list. If model is specified without MODEL=, language without LANGUAGE= must be the first item and model must be the second item in the extrinsic-spec-arg-list. If external-name is specified without EXTERNAL_NAME=, language without LANGUAGE= must be the first item and model without MODEL= must be the second item in the extrinsic-spec-arg-list.
• The forms with LANGUAGE=, MODEL=, and EXTERNAL_NAME= may appear in any order except as prohibited above.

  Note that these rules for extrinsic-spec-arg-list are as if EXTRINSIC were a procedure with an explicit interface with a dummy-arg-list of LANGUAGE, MODEL, EXTERNAL_NAME, each of which were OPTIONAL.

• In language, values of scalar-char-initialization-expr may be:
  • "0DHPF"0D, referring to the HPF language; if a model is not explicitly specified, the model is implied to be "0DGLOBAL"0D;
  • "0DFORTRAN"0D, referring to the ANSI/ISO standard Fortran language; if a model is not explicitly specified, the model is implied to be "0DSERIAL"0D;
  • "0DF77"0D, referring to the former ANSI/ISO standard FORTRAN 77 language; if a model is not explicitly specified, the model is implied to be "0DSERIAL"0D;
  • "0DC"0D, referring to the ANSI standard C programming language; if a model is not explicitly specified, the model is implied to be "0DSERIAL"0D; or
  • an implementation-dependent value with an implementation-dependent implied model.

  Note that, for most implementations, "0DC"0D will only be allowed for function-stmts and subroutine-stmts occurring in an interface-body.

• If language is not specified it is the same as that of the host scoping unit.
• In model, values of scalar-char-initialization-expr may be:
  • "0DGLOBAL"0D, referring to the global model,
  • "0DLOCAL"0D, referring to the local model,
  • "0DSERIAL"0D, referring to the serial model, or
  • an implementation-dependent value.

• If model is not specified or implied by the specification of a language, it is the same as that of the host scoping unit.
• All languages and models whose names begin with the three letters HPF are reserved for present or future definition by this specification and its successors.
• In external-name, the value of scalar-char-initialization-expr is a character string whose use is determined by the extrinsic kind. For example, an extrinsic kind may use the external-name to specify the name by which the procedure would be known if it were referenced by a C procedure. In such an implementation, a user would expect the compiler to perform any transformations of that name that the C compiler would perform. If external-name is not specified, its value is implementation-dependent.

H614 extrinsic-kind-keyword

is HPF or HPF_LOCAL or HPF_SERIAL

• EXTRINSIC(HPF) is equivalent to EXTRINSIC("0DHPF"0D,"0DGLOBAL"0D). In the absence of an extrinsic-prefix an HPF compiler interprets a compilation unit as if it were of extrinsic kind HPF. Thus, for an HPF compiler, specifying EXTRINSIC(HPF) or EXTRINSIC("0DHPF"0D,"0DGLOBAL"0D) is redundant. Such explicit specification may, however, be required for use with a compiler that supports multiple extrinsic kinds.
• EXTRINSIC(HPF_LOCAL) is equivalent to EXTRINSIC("0DHPF"0D,"0DLOCAL"0D). A
  main-program whose extrinsic kind is HPF_LOCAL behaves as if it were a subroutine of extrinsic kind HPF_LOCAL that is called with no arguments from a main program of extrinsic kind HPF whose executable part consists solely of that call.
• EXTRINSIC(HPF_SERIAL) is equivalent to EXTRINSIC("0DHPF"0D,"0DSERIAL"0D). A main-program whose extrinsic kind is HPF_SERIAL behaves as if it were a subroutine of extrinsic kind HPF_SERIAL that is called with no arguments from a main program of extrinsic kind HPF whose executable part consists solely of that call.
• All extrinsic-kind-keywords whose names begin with the three letters HPF are reserved for present or future definition by this specification and its successors.

Advice to implementors.Other languages or models may be defined and provided by compiler vendors. Although not part of this HPF specification, they are expected to conform to the rules and spirit of HPF extrinsic kinds.

An implementation may place certain restrictions on the programmer; moreover, each extrinsic kind may call for a different set of restrictions.

For example, an implementation on a parallel processor may find it convenient to replicate scalar arguments so as to provide a copy on every processor. This is permitted so long as this process is invisible to the caller. One way to achieve this is to place a restriction on the programmer: on return from the subprogram, all the copies of this scalar argument must have the same value. This implies that if the dummy argument has INTENT(OUT), then all copies must have been updated consistently by the time of subprogram return.

(End of advice to implementors.)