tempcomp and fallbackdrift

Hi,

can someone please explain the chrony.conf directives "fallbackdrift" and
"tempcomp"?

When are tempcomp corrections applied to the system clock? Additional with
the slewing from the source synchronisation? Will the temcomp corrections
applied in holdover mode additive to fallbackdrift corrections?

What are the correctiona to system clock due to fallbackdrift after
max-interval?

I am aiming for best holdover performance, when no sync is possible for a
long time. No stratum 0 or PPS signal available.

Christoph