For each socket to be tested, the SELECTEX call can check for an existing exception condition. Two exception conditions are supported:

• The calling program (concurrent server) has issued a GIVESOCKET command and the target child server has successfully issued the TAKESOCKET call. When this condition is selected, the calling program (concurrent server) should issue CLOSE to dissociate itself from the socket.
• A socket has received out-of-band data. On this condition, a READ will return the out-of-band data ahead of program data.

To test whether any of several sockets have an exception condition, set the ESNDMSK bits representing those sockets to 1. When the SELECTEX call returns, the corresponding bits in the ERETMSK indicate sockets with exception conditions.