如何检查字符串是否为有效的XML元素名称？

怎么样

/A(?!XML)[a-z][w0-9-]*/i

用法：

if (preg_match('/A(?!XML)[a-z][w0-9-]*/i', $subject)) {    # valid name} else {    # invalid name}

说明：

A  Beginning of the string(?!XML)  Negative lookahead (assert that it is impossible to match "XML")[a-z]  Match a non-digit, non-punctuation character[w0-9-]*  Match an arbitrary number of allowed characters/i  make the whole thing case-insensitive