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Characteristics of Procedures

The characteristics of dummy data objects and function results as given in the Fortran standard (F95:12.2) are extended to include also the HPF-characteristics of such objects, which are defined recursively as follows:

• A processor arrangement has one HPF-characteristic: its shape.
• A template has up to three HPF-characteristics:
  1. its shape;
  2. its distribution, if explicitly stated;
  3. the HPF-characteristic (i.e., the shape) of the processor arrangement onto which it is distributed, if explicitly stated.
• A dummy data object has the following HPF-characteristics:
  1. its alignment, if explicitly stated, as well as all HPF-characteristics of its align target;
  2. its distribution, if explicitly stated, as well as the HPF-characteristic (i.e., the shape) of the processor arrangement onto which it is distributed, if explicitly stated.
• A function result has the same HPF-characteristics as a dummy data object. Specifically, it has the following HPF-characteristics:
  1. its alignment, if explicitly stated, as well as all HPF-characteristics of its align target;
  2. its distribution, if explicitly stated, as well as the HPF-characteristic (i.e., the shape) of the processor arrangement onto which it is distributed, if explicitly stated.

Rationale.In case an explicit interface is given by an interface block, the Fortran standard specifies what information must be specified in that interface block; it does this using the concept of a Fortran characteristic. Characteristics of dummy data objects, for instance, include their types. Characteristics must be specified in interface blocks; F95:12.3.2.1 in the Fortran standard states

An interface body specifies all of the procedure's characteristics and these shall be consistent with those specified in the procedure definition ...

Normally, an interface block for a procedure is a textual copy of the appropriate declarations of that procedure. This Section simply says that such a textual copy must include any explicit mapping directives relevant to dummy arguments of the procedure. (End of rationale.)