OPEN: ASYNCHRONOUS Specifier

The ASYNCHRONOUS specifier indicates whether asynchronous I/O is allowed for a unit. It takes the following form:

ASYNCHRONOUS = asyn

asyn	Is a scalar expression of type default character that evaluates to one of the following values: 'YES' Indicates that asynchronous I/O is allowed for a unit. 'NO' Indicates that asynchronous I/O is not allowed for a unit.

The default is 'NO'.