PHONOLOGY: order of rules such that one rule destroys the input of another rule.
EXAMPLE: consider the following two rules proposed by Schane (1968) for French: (a) a vowel is nasalized before a nasal, and (b) a nasal is dropped in syllable-final position. To derive the output [bő] of bon, rule (a) must be applied
before rule (b). If (b) would precede rule (a) it would bleed rule (a): the vowel cannot be nasalized anymore and [bő] could not be derived.