\spacefactor command: Assigning an explicit space factor ¶As mentioned above, the \spacefactor command allows explicitly
setting the current space factor to the given value, as in
\spacefactor=3000
Such an explicit assignment is almost never needed; the following
sections describe the higher-level commands that are typically used.
You can see the current value with \the\spacefactor or
\showthe\spacefactor, as usual with parameters. It can be used
only in paragraph mode or LR mode (see Modes).
Finally, not normally related to \spacefactor itself, despite
appearances, if you get errors like:
You can't use `\spacefactor' in vertical mode You can't use `\spacefactor' in math mode Improper \spacefactor
then you have likely tried to redefine an internal command, and
LaTeX thinks it’s not typesetting normal text at the point of the
error. See \makeatletter & \makeatother.