Date: 07 Jul 1993 12:45:34 -0400 (EDT) From: Michael Downes Subject: Around the Bend #9, answer Sender: ITeX-Mgr@SHSU.edu To: info-tex@shsu.edu Reply-to: Michael Downes Message-id: <742063535.36965.MJD@math.ams.org> X-ListName: TeX-Related Network Discussion List "In internal vertical mode, if the preceding item on the list is a "vbox, can you do this: \unvbox\lastbox? The answer is no. If you tried it, you would have seen the error message: ! Missing number, treated as zero. \lastbox l.3 \unvbox\lastbox ? h A number should have been here; I inserted `0'. (If you can't figure out why I needed to see a number, look up `weird error' in the index to The TeXbook.) \lastbox does not return a box register number, which is what \unvbox requires; instead, \lastbox returns a object in the sense of the TeXbook, chapter 24, p 278. There are only a few TeX commands that accept a object as their argument (\shipout, \setbox, \leaders, ...), and \unvbox is not one of them.