Cable switch F or Fdp

Can anyone tell me the difference between the F and Fdp versions please?
A few years ago, Jessops sold me the F model for my Z1-P and it appears to work fine but I believe the Fdp is the recommended version for my camera.

Thanks.

The F is a square section I think( 4 sides), the newer one has the corner cut off (5 sides). I used an F with a SFXN, but was slightly tricky to fit to the Z1P because of the extra corner

Thankyou for that Gordon, I guess I'm not losing any functionality then.
They must both be interchangeable as mine fits both my SFX and Z1-P.
Mine does however have the corner removed - as you described but I have noticed that the compartment on the rear of the cable release control will not accomodate the contact cover from the Z1-P.
As Pentax provided a compartment in the strap for such small items it seems strange that they would go to the trouble of redesigning the release.

Cheers
Kimbo.

As I now have both versions of the cable switch, I can confirm that they do appear to be interchangeable.
I've tried them both on my SFX and Z1-P bodies and they work in exactly the same way, so why is the FDP version excusively designed for the Z1-P?

The switches are identical except for a small 'box' near the plug end of the FDP switch - some sort of power regulator perhaps!

As far as I know, all cameras from the SFX to the Z1 use the cable switch F but the Z1-P uses the FDP version but I don't think it has anything to do with the panoramic function because the other Z series 'P' cameras (Z20-P, Z50-P etc) also use the F version.........or am I wrong?

I think the Z70-P was the last of the Z series cameras, anyone know which cable switch was recommended for that one? - can't find a downloadable manual for it!