Note added to the “Precomposing layers for a new animation” section (page 50 in the printed book).
The Precompose dialog box illustration in the book may vary slightly from the one you see on your screen. In After Effects 12.1 and later, the Precompose dialog box includes the new Adjust Composition Duration To The Span Of The Selected Layers option. (Select the new option to create a composition that has the same duration as that spanned by the selected layers.)
3.147.126.33