JavaScript reference for Apple .pkg makers

I have never seen it mentioned anywhere and just stumbled across Apple's developer documentation on the AppleScript objects that are available to installer writers. I probably have totally missed something obvious telling me where to find it, but I have always just used what I have gleaned from taking Apple's installers apart, but now have actual documentation:

http://developer.apple.com/mac/library/documentation/DeveloperTools/Reference/InstallerJavaScriptRef/

For those writing scripts that check for the presence of things to decide what to install (I am looking at you iLife Support team) I will pointedly reference the "target" item, and it's "mountpoint" property.