Hi Juergen,
I know the file
was successfully opened, because I print the argument that is going to
be passed to do the read, 2 0 16, and it has successfully fetched the
file size.
The value error is strange, because it branches
to the dyadic case only after using NC to check existence of the left
argument to SVOPAIR. Then it gives a value error on PID, but if you
print it after the function is suspended, it is 210.
So something odd is clearly going on there, independent of what GNU APL's AP210 does or does not support.