Major Description
From the rfc2396:
"
Other characters are excluded because gateways and other transport
agents are known to sometimes modify such characters, or they are
used as delimiters.
unwise = "
{" | "}" | "|" | "\" | "^" | "[" | "]" | "`"
Data corresponding to excluded characters must be escaped in order to
be properly represented within a URI.
"
The URLValidator doesn't check if an "unwise" character is used as unescaped char and subsequently reports a URL as valid if it has an unwise character in it. There are some applications out there which break eating such a URL.
