How to check if string is a valid XML element name?

Question

I need a regex or a function in PHP that will validate a string to be a good XML element name.

Form w3schools:

XML elements must follow these

Answer 1

if (substr(strtolower($text), 0, 3) != 'xml') && (1 === preg_match('/^\w[^<>]+$/', $text)))
{
    // valid;
}