[tex-k] do not understand

Wolfgang Helbig helbig at mailbox.org
Sun Dec 20 14:19:16 CET 2020

Some days ago, I wrote:
> Hello,
> according to the answer to ex.14.10 (A97), the sequence \break\break 
> causes two line breaks, i.e. an empty line. This is confirmed by a 
> simple TeX run.
> But according to the following paragraph, all discardable items after 
> a break are removed until to something non-discardable.
> Now, \break is a \penalty-10000 and penalties are discardables. From 
> this I'd expect the second \break in \break\break to be discarded.
> Did I miss something? Is this one of the little white lies? Or is this 
> an error in the TeXbook?
This is neither a little white lie nor an error in the TeXbook! Instead 
I  should have read the whole sentence: "... TeX removes all discardable 
items that follow the break, until coming to something non-discardable, 
***or until coming to another chosen breakpoint.***" Since the second 
\break is a chosen breakpoint, it will not be discarded! Thanks to Karl, 
I can see clearly now.


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