CheckOrder←{
⍝ Return indices of major cells in ⍵ that differ from ⍵ sorted ascending
     ⎕IO←0   ⍝ Set index origin to 0 to match examples
⍝ Simple vector (list) case, return indicies of elements in ⍵
     sorted←⍵[⍋⍵]
     ⍸⍵≠sorted
⍝ General array case
⍝ https://aplwiki.com/wiki/Total_array_ordering
⍝ https://aplwiki.com/wiki/Leading_axis_theory
     sorted←(⍋⊂⍛⌷⊢)⍵
     ⍸⍵(≢⍤¯1)sorted
 }