Can php URLs have numeric parameters?

Is this valid?:

http://www.SomeURL.com/Index.php?123=开发者_C百科xyz

Will I be able to access the value 'xyz' under the key '123' the same ways as usual?

Yes, it's completely possible. It's also very easy to try by yourself.

Yes you can do this.

$_GET['123']

Yes this is something you can do.