rule xxx
timer(int 10 ) # not the missing colon
when
then
System.out.println( "CRONTAB" );
end

causes:

Exception in thread "main" org.drools.RuntimeDroolsException: Error parsing time string: [ int ]
at org.drools.time.TimeUtils.parseTimeString(TimeUtils.java:127)
at org.drools.rule.builder.RuleBuilder.buildTimer(RuleBuilder.java:320)
at org.drools.rule.builder.RuleBuilder.buildAttributes(RuleBuilder.java:139)
at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:92)
at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:1889)
at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:755)
at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:365)
at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:543)
at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:28)