HP-42S ESD self-test

[Yriarte]

The self-test activated by the second key on the second row (RCL) in my HP-42S, will display the text ESD in the screen and the beeper starts beeping. This test can be stopped by pressing a random button. What's ESD meaning and what is tested?
Anyone can help me?.
Waiting your answers.
Best regards,

Adrian

Edited: 23 Oct 2013, 6:08 p.m.

[Eric Smith]

Electrostatic Discharge.

The ESD self-test is not useful without specialized test equipment.

[Yriarte]

Thanks a lot!
Regards.