[tex-k] Possible Bug in The TeXbook

Sebastian Miele sebastian.miele at gmail.com
Tue Nov 5 00:19:50 CET 2019

Depending on the exact interpretation of "right", the unique line

inserted at the right end of both the parameter text and the replacement text.

in knuth-dist/tex/texbook.tex may not be correct. If "right" is meant to
mean "correct", then the line may be considered correct. (Although,
strictly, the left brace is part of the parameter text, but not of the
replacement text. The replacement text always must be surrounded by
braces that get eliminated.)

If "right" means the direction opposite to the left, then it is wrong.
When I encountered the sentence I read it that way and had a (short)
hard time (not) understanding it. The example directly following the
sentence completely clarifies what is intended, and somewhat later I
found that "right" might also mean "correct". English is not my native
language. On the other hand my English is not that bad either. I may be
"right" in my first interpretation.

A replacement like

inserted at both the end of the parameter text and before the
replacement text.

would be completely clear to me.

Best wishes

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