>
> Are all EPROM versions of Microchips uc's UV erasable?

Nope.

> And if so what does Microchip mean by O.T.P. technology?

One Time Programmable.

The OTP's have an EPROM. However they don't have the erasure window nor
the ceramic case. So they cannor be erased under normal circumstances by
the average UV eraser. You could erase them if you can get the cover off.

BAJ