Seems modern scholars apply this rule (1.4.2) in a much narrower scope. The researcher argues that 1.4.2 is actually a metarule that applies to all of Aṣtādhyāy

Seems modern scholars apply this rule (1.4.2) in a much narrower scope. The researcher argues that 1.4.2 is actually a metarule that applies to all of Aṣtādhyāyī. Covered near the end of the 1st chapter in his thesis.