1.4 Familiarizing yourself - test.cf has errors

I've created /tmp/test.cf, containing the example cfengine test from "  
section 1.4  Familiarizing yourself " of the documentation.

Using cfengine 3.0.0.b6 on CentOS 5.2, cf-promises -f /tmp/test.cf, I  
get the result:

cf3:/tmp/test.cf:38,27: Constraint lvalue on_change is not allowed in  
'classes' constraint near token '}'
cf3:/tmp/test.cf:38,27: Constraint lvalue on_failure is not allowed in  
'classes' constraint near token '}'

I don't want to be overly critical, but it is hard to understand why  
an example copied/pasted straight from the documentation  does not  
seem to work.  Is the example wrong, or does cfengine3 have a bug?