Try
js new FITSKeyword("name","T").isBoolean
It returns true under Windows (correct) and false under Fedora...
Maybe it is the undocumented way to check on which OS we are running ?
![Wink ;)](http://pixinsight.com/forum/Smileys/default/wink.gif)
Both are fresh re-install of RC5 with latest patches (March 31) and cleaned preferences.
-- bitli