how to get the full list of ANT built-in properties

[Bill . J . Fellows]

Hello,
I see that Diane very abily answered this question back on 20 April but 
my question is, beyond being in know as a developer, how would you go 
about determing this stuff?  

I think I may have just answered my question though by coding up her 
lil' no op example and run it with -debug.  That is how one would see 
what is available on their system, yes?  

Any other way?  Perhaps something like <echo message="${env}" />

/bill