M = 1000 and comes "first", D = 500 and comes "second", etc.

Sure, M is left most, and D is second left most. But your examples have contrary input. "XIX" => "....X.I" contradicts "IX" => "....X.." as far as I can tell.

---
$world=~s/war/peace/g

In reply to Re^2: Help with a Regex by demerphq
in thread Help with a Regex by planetscape

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