Please can anyone help me with this query?

When I came to make a drop down list for data entry in a cell, I used
the method:
Select cellMenu
BarDataValidationAllow:ListSource:Yes,No,Undec ided.

When I went to the origial workbook I was using for an example and go
to: Select cellMenu BarDataValidationAllow:ListSource: The source
field shows: =Choices.

The only cell in the 3 sheet example workbook showing the entry:
Choices, is the heading of the column where the drop down
"Yes,No,Undecided" cells are located. There is no text defining the
Yes,No,Undecided list choices there.
How would go about finding the place in the workbook where this
information is kept?

TIA
Lila