Function keys in F mode

In EDT's F mode, it is possible to initiate a large number of actions using function keys. The [K2] key is exceptional here since, on the one hand, it is the only function key that also operates in L mode and, on the other, its action can be completely suppressed, for example in noninterruptible procedures or when EDT has been called as a subroutine (e.g. in the POSIX shell).