Policy/recommendation on compiling with version 1.4 vs. 1.5?

["Eric Lavarde - Debian" <deb@zorglub.s.bawue.de>]

Hi,

my understanding of the differences between Java 1.4 and 1.5 is that
programs compiled with Java 1.5 might not work in the JVM 1.4, but the
other way around should always work.

So my questions:
1. is this correct?
2. if yes, shouldn't the consequence for Debian be, even though Sun Java
is not officially supported, a recommendation or policy that Java packages
should be compiled with Java 1.4, if possible?

Thanks, Eric

-- 
Eric de France, d'Allemagne et de Navarre