I think you should remove the period, colon, and forward slash from the function; the period and slash are common to all URI's, and the colon is commonly used to designate a port after the hostname in a URL.
Also, the question mark, equals sign, and ampersand are used in the URL's of most sites which utilize some form of server-side scripting, such as PHP or ASP, to generate dynamic content.
Other vaild URI characters found in the function are as follows:
#
+
- (hyphen)
_ (underscore)
~
There may be others, but those are the ones that caught my eye.