Why did class version go to 50?

Sorry if this is posted somewhere else but it doesn't seem to be possible to search just the Java Compiler board...Why was the class file version incremented to 50 in Java 6? Now, if I compile with Java 6 I can't run in Java 5. Is there a way around this?
[271 byte] By [jordanza] at [2007-11-26 14:30:05]
# 1
http://blogs.sun.com/ahe/entry/javac_default_class_file_version
PeterAhea at 2007-7-8 2:24:40 > top of Java-index,Developer Tools,Java Compiler...
# 2
Thanks.FYI - for others. Add "-target 5" to your javac command line to work around this.
jordanza at 2007-7-8 2:24:40 > top of Java-index,Developer Tools,Java Compiler...