What do % signs mean in a url?
url
Solution
The reference you're looking for is RFC 3987: Internationalized Resource Identifiers, specifically the section on mapping IRIs to URIs.
RFC 3986: Uniform Resource Identifiers specifies that reserved characters must be percent-encoded, but it also specifies that percent-encoded characters are decoded to US-ASCII, which does not include characters such as `è`.
RFC 3987 specifies that non-ASCII characters should first be encoded as UTF-8 so they can be percent-encoded as per RFC 3986. If you'll permit me to illustrate in Python:
>>> u'è'.encode('utf-8')
'\xc3\xa8'
Here I've asked Python to encode the Unicode `è` to a string of bytes using UTF-8. The bytes returned are `0xc3` and `0xa8`. Percent-encoded, this looks like `%C3%A8`.
The parenthesis also appearing in your URL do fit in US-ASCII, so they are percent-escaped with their US-ASCII code points, which are also valid UTF-8.
So, no, there is no simple 16×16 table—such a table could never represent the richness of Unicode. But there is a method to the apparent madness.
Problem
When I copy paste this Wikipedia article it looks like this. http://en.wikipedia.org/wiki/Gruy%C3%A8re_%28cheese%29 However if you paste this back into the URL address the percent signs disappear and what appears to be Unicode characters ( and maybe special URL characters ) take the place of the percent signs. Are these abbreviations for Unicode and special URL characters? I'm use to seeing \u00ff, etc. in JavaScript.