Evaluating XPath Expresssions

XPath Result of XPath Evaluation
for $i in tokenize('12, 16, 3, 99', ',\s*') return $i
12 16 3 99
for $i in tokenize('12xx16XX3xX99', 'xx', 'i') return $i
12 16 3 99
for $i in tokenize('12xx16XX3xX99', 'xx') return $i
12 16XX3xX99