6.1. Writing ClassAd expressions
  Example 6.6. A typical ClassAd
  Memory    = 128
  [comment] RHEL 6 can't run on 128 megs of ram. Suggest updating to a modern machine.
  
  They can not start with a number.
  [typo] WUG suggests s/can not/cannot/
  
  Operators
  The unary negation operator of - takes the highest precedence in a string. In order, operators take the following precedence:
  
      - (unary negation)
      * and /
      + (addition) and - (subtraction)
      < <= >= and >
      == != =?= and =!=
      &&
      || 
  [comment] Do we need the first sentence as unary negation is #1 in the list?
  
  and exploit the dont care" properties
  [typo] contraction WUG says: s/dont/do