Again, trying to read through and understand zshexpn… https://www.mankier.com/1/zshexpn#Filename_Generation-Globbing_Flags The subsection is Globbing Flags within Filename Generation with both the b and m flags is a curious phrase: > Activate backreferences for parenthesised groups in the pattern; this does not work in filename generation. Why does it say “this does not work in filename generation” ? Using their example for the m flag: > arr=(veldt jynx grimps waqf zho buck) > print ${arr//(#m)[aeiou]/${(U)MATCH}} I can change the “print” to “touch” and it touches the files and change it to “rm” and it removes the files. My fear here is that I’m missing something rather significant such as what precisely is “filename generation”