Is this valid?:
http://www.SomeURL.com/Index.php?123=xyz
Will I be able to access the value 'xyz' under the key '123' the same ways as usual?
Is this valid?:
http://www.SomeURL.com/Index.php?123=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.