\fB\-par=\fR<n>
.IP
Set the number of script verification threads (\fB\-10\fR to 15, 0 = auto, <0 =
leave that many cores free, default: 0)

\fB makes the -10 bold, as if it were a parameter rather than a value.

(Additionally, the -10 comes from the system of whoever ran the gen-manpages script, and should probably be generated deterministically here...)