If the condtion element for a jfc schema defaults to "true" or "false" for the true and false attrubute, it becomes impossible to create some multiple choice logic For example,

 <condition name="compiler-phase-threshold" true="60 s">
   <test name="compiler-level" operator="equal" value="normal"/>
 </condition>

 <condition name="compiler-phase-threshold" true="10 s">
   <test name="compiler-level" operator="equal" value="detailed"/>
  </condition>

  <condition name="compiler-phase-threshold" true="0 s">
   <test name="compiler-level" operator="equal" value="all"/>
  </condition>
 
In this case, only when the condition evaluates to true should a modification of compiler-phase-threshold occur. It would be possible to set a default for "true", since it is always possible to negate an expression with <not>, but expressions can be kept simpler if we don't set defaults at all.