>>>>Anyway, I'm looking for a definition of a url format (ie structure and valid chars) Once I have that I may have a go at it
>>>
>>>Ok, I'll post a reference to that thread in a second - give me 2 minutes.
>>
>>
>>I think this defines the valid format http://www.w3.org/Addressing/URL/url-spec.html
>
>Yes, but too complex for me. Good luck!

Not really that complex if one takes the time to solve each piece at a time