INQUIRE: ASYNCHRONOUS Specifier

The ASYNCHRONOUS specifier asks whether asynchronous I/O is in effect. It takes the following form:

ASYNCHRONOUS = asyn

asyn
Is a scalar default character variable that is assigned one of the following values:

'NO' If the file or unit is connected and asynchronous input/output is not in effect.
'YES' If the file or unit is connected and asynchronous input/output is in effect.
'UNKNOWN' If the file or unit is not connected.