Ada 2012 Reference Manual
J.15.13 Pragma Asynchronous
Syntax
pragma Asynchronous (local_name);
Static Semantics
For an implementation that supports Annex E, a pragma Asynchronous specifies that the Asynchronous aspect (see E.4.1) for the procedure or type denoted by local_name has the value True.
Legality Rules
The local_name of a pragma Asynchronous shall denote a declaration that may have aspect Asynchronous specified.