System Variable to Identify Background Task?

Hi,

Is there any system variable to identify whether a FM is called in background task, similar to SY-BATCH which is set when program is run in background mode.

[I have checked SY-BATCH, it is not set in case of BACKGROUND TASK.]

I need to put some condition inside the FM when it is run in background task as below:

CALL FUNCTION 'Z_TEST'
    IN BACKGROUND TASK
    DESTINATION 'NONE'
...
...
.

Is there any way to identify this using any existing system parameters or any other FM ?