Bill Long wrote:

On the surface, the main area of difference between VOLATILE and ASYNCHRONOUS is that a standard-conforming program is not allowed to improperly reference or define an asynchronous variable in a part of the code where it is subject to asynchronous activity. There is nothing "on the surface" about this---it is a core and important difference as I already explained. Just like coarrays are rather distinct from VOLATILEs, so are targets of async I/O. I don't care if Cray's compiler treats them the same internally, that is a quality of implementation issue. But the semantics are rather different. Aleks