Converting %xx chars to readable

In a page like

http://www.dmoz.org/World/Greek/%c1%e3%ef%f1%dd%f2/

there are 3 types of chars:
a) the %xx format used in the URL

b) the 'internal' format which is what you see when you view the source HTML and what I am currently using in PHP in the form:

$char['url'] = "%c0";
$char['readable'] = "À";
$this->converter[] = $char;

c) the visual representation seen by the user (e.g. the actual Greek characters in this case).

Now, my questions:
1) is there a list of conversion chars?
2) is there a function in PHP to do this?

Thanks!

Thanks anyway!

What I needed was:
http://be.php.net/manual/en/function.rawurldecode.php

And if you go to www.localpin.com and select, for example, the Russian language (from the language pull-down in the top-right), you will see the Russian characters display correctly.

Not that I speak any Russian