As a consequence of this rule, all voiceless plosives which make part of a word-final consonant cluster are glottalized.
If the rule which deletes word-final /-ə/ in French had been applied before another rule which deletes word-final consonants before another consonant, this would have been an example of feeding order and the "final output" form (surface form) would have been [pəti njɛs] instead.
In the given case, it is the application of the rule deleting word-final consonants which has thus become opaque in French.
In historical linguistics, a sequence of rules in counterfeeding order is called a chain shift.
A chain shift can be presented graphically like the following: where only one rule can apply.