Csound 5.12.1 from source, Debian

The manual page lists modes 1-4 for max_k; experimentation shows it's 0-3.
Also, modes 1 and 2 don't do what is listed (listed as modes 2 and 3,
that is). See attached .csd file. If the opcode output the "actual
maximum" value between the changes of the k-trigger, it would go below
zero when the sine is below zero for several cycles; but it levels off
at 0. In mode 2, the same thing, but only negative and zero. Maybe a
better explanation for mode 1 would be "maximum value or 0, whichever
is higher." Although I suspect that's not the intended behavior; it
doesn't seem very useful.

-Chuckk