<html xmlns:firstNS> <head> <?import namespace="firstNS" implementation="makeRed.htc"> <script> function addNS(){ namespaces.add(secondNS, someFile2.htc); namespaces.add(thirdNS, someFile3.htc); } </script></head> <body> <button onclick="addNS();">Add namespace names</button> </body> </html>