Yes-- in other words, what they most likely meant to say, is that the entire measurement around of the garment should be a total of 24". So that would mean the back is half of that-- 12", and the right front would be 6", and the left front should be 6". The fronts may not be each exactly 6", as there will be some overlap for buttons and button holes, or a zip, etc. But that adds up to 24" total.
I asked about the publisherof the book because I wondered if a had it (and the title "Easy Baby Knits" seems to be a very popular one:) ). But I don't.:sad: