yogi_Use VLOOKUP In Google Old Sheets For MultiColumn Search_Key

                                          Google Spreadsheet   Post  #1473
Yogi Anand, D.Eng, P.E.      ANAND Enterprises LLC -- Rochester Hills MI     www.energyefficientbuild.com.   Jan-05-2014
question by mcjtom (https://productforums.google.com/forum/#!category-topic/docs/spreadsheets/SRGdEhVvdFc)
Adam's/ahab's Vlookup as array formula - multicolumn search criterion?

I was playing with the Adam's/ahab's amazing machine:

=arrayformula(iferror(vlookup($A2:$A,'Helper_01'!$A:$I,7*sign(row($A2:$A)),false)))

By mistake I change the first Vlookup argument to multi-column array (A2:B). The formula still worked, but what does it actually do?  

Is the first column of 'Helper_01'!A:I range compared to either of both columns of the A2:B search criterion, or just one of them (but which one)?

Cheers!

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