When you code an ACL in TPX to automate the logon process for an user to an application the first statement likely is WINP (Wait INPut). This statement lets the ACL wait for the application to send the first datastream.
The ACL continues processing after a datastream was reached from the application and the keyboard is unlocked. Then the ACL processes the next statement. That likely will search the data stream for content and then enter data depending on the received data stream.
The ACL will send the input to the application using one of the “Key pressing simulator”-Commands ENTER, PF n, PA n and CLEAR. You need to be aware that all these Commands send the appropriate key to the application AND wait for the next datastream as response from the application.
There is no need for an additional WINP! So if you code
ENTER
the application processes the screen and returns a new data stream. Until that data stream the ACL pauses.
But if you would code the two lines
ENTER
WINP
the ACL waits for a second data stream from the application. As that second data stream will not appear the ACL is in a deadlock.