static S ctxParsingRules() {
  ret [[
<identifier> = ruleid
<int> = ruleid
<int> <identifier> = ruleid
<ruleid> - <ruleid> = ruleid

RULE <ruleid> ( <exp> ) = rule

// e.g. (MATCH1==MATCH5) 
<identifier> = = <identifier> = comp
<comp> = expX

// bracketing combines top and bottom
( <exp> ) = bracket
<bracket> = expX

// primitive expressions are at top level
<quoted> = expX

// as is negation
! <expX> = neg
<neg> = expX

// now come the lower levels
<expX> = exp3

<exp2> & & <exp3> = and
<exp3> = exp2
<and> = exp2

<exp1> | | <exp2> = or
<exp2> = exp1
<or> = exp1

// lowest level
<exp1> = exp
]];
}