For the Acquired date, in the Import dialog I had to select "Various".
Then, I went into menu > View > Forms > Form 1099-B Wks > QuickZoom to Cap Asset Sales. (N.B. the little status line at bottom, with the up arrow to open the corresponding form, said "No Form".)
Then, in the field where TT automatically entered "VARIOUS", I was able to type "inherited". (N.B. at first I typed "INHERIT", which was highlighted in red as an error. When I changed it to "inherited", the color changed back to the normal blue; so I think (a) this field is validated and (b) "inherited" is correct.)
