Lufthansa A310 White-light rear small Beacon?

[JanetFlight]

Hi to All...For many years i've been trying to find an explanation to this question but without any plausible sucess. So im kindly here asking now for your precious help.
I've noticed for many times here on my Local Airport, Faro-LPFR, during the old nice days of DLH's A313, that near the rear under fuselage it had some sort of "Low intensity slow-flashing white beacon". I´ve asked a few times about its purpose, reminding me of the similar ones on the TU-154's (wich honestly i also never really got it too), even to some crew, but without any explicit or plausible answer...So, anyone here could led me to some light on this.:confused:
Tanx for the kind attention...Cheers:ok:

[IFixPlanes]

This is part of the ground crew (MECH) call system.
If the crew push the CALL-Button a horn will sound and the light is flashing.
Light can be extinguished by pressing the reset-button.

You find the call and the reset button left of the strobe light switch.
Upper left area in this picture. (http://www.airliners.net/photo/TAP-Portugal/Airbus-A310-304/0936660/L)

[Terry McCassey]

. . Worked with some A320's that have them too, often more useful than the mechanic call horn.

[JanetFlight]

Many tanx my friends;)