Read the 1040 Instructions.
Thanks.
I missed the part I needed because it’s on a page with a big heading of “Standard Deduction Worksheet for Dependents”. Neither of us are ‘dependents’, and the chart for ‘Born Before January 2, 1954’ has no bold heading; I thought it was just more stuff about dependents. It seems like poor formatting; but at least I’ve got it now.
(Speaking of formatting, I’m still looking for that ‘postcard-size tax form’...)