Banned files match, example question

[Gregory Sloop]

I'm looking at these two banned files defs/matches. [From the Ubuntu default configs]

---
  qr'.\.(exe|vbs|pif|scr|bat|cmd|com|cpl)$'i, # banned extension - basic

# qr'.\.(ade|adp|app|bas|bat|chm|cmd|com|cpl|crt|emf|exe|fxp|grp|hlp|hta|
#        inf|ins|isp|js|jse|lnk|mda|mdb|mde|mdw|mdt|mdz|msc|msi|msp|mst|
#        ops|pcd|pif|prg|reg|scr|sct|shb|shs|vb|vbe|vbs|
#        wmf|wsc|wsf|wsh)$'ix,  # banned ext - long

---

But I'm confused. Why does the first match use:
$'i
vs
$'ix for the second?

It's matching to i in the first, but ix in the second?

Why?

Sorry if I'm missing something obvious, but I just don't get it.

-Greg
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