"Iain Churches" wrote

It's quite simple. There are two types of TRS 6.3mm jacks.
The one popularly known as the GPO type,

The "GPO" ceased to exist in the 1960s. And the B gauge plug was designed by
Western Electric, not the GPO.

with the small
tip, is used in music studios only on patch bays.

Whilst outside music studios it is very widely used for balanced audio in a
wide variety of applications.

Cables with
one of these at either end are referred to as patch cords.

*Any* short cable with the same sort of plug on each end intended to be used
on a patch bay is a "patch cord". Such as the MUSA patch cords widely used
on video patchbays.

The other type, with the larger ball tip, is used everywhere
else (music amps, keyboards etc) It is referred to as a
balaced jack (add plug if you like:-)

Refered to by who?, you?

Many people call it the "stereo" plug since it is widely used to carry
unbalanced stereo.

and usually has an
XLR on the other end of the cable.

Does it? even when it has a pair of heaphones on the other end?

You have a way of referring to these plugs that may mean something to you
and your colleagues. But can only cause confusion when used outside your own
small circle.

David.