`\hss`

Synopsis:

\hss

Produce a horizontal space that is infinitely shrinkable as well as
infinitely stretchable (this command is a TeX primitive). LaTeX
authors should reach first for the `\makebox`

command to get the
effects of `\hss`

(see `\mbox`

& `\makebox`

).

Here, the first line’s `\hss`

makes the Z stick out to the right,
overwriting the Y. In the second line the Z sticks out to the left,
overwriting the X.

X\hbox to 0pt{Z\hss}Y X\hbox to 0pt{\hss Z}Y

Without the `\hss`

you get something like ‘`Overfull \hbox
(6.11111pt too wide) detected at line 20`’.