internationalization - Which encoding uses the x (backslash x) prefix?

Question

I'm attempting to decode text which is prefixing certain 'special characters' with x. I've worked out the following mappings by hand:

x28   (
x29   )
x3a   :

e.g. 12x3a39x3a03 AM

Does anyone recognise what this encoding is?

Answer 1

It's ASCII. All occurrences of the four characters xST are converted to 1 character, whose ASCII code is ST (in hexadecimal), where S and T are any of 0123456789abcdefABCDEF.