To amswer my own questions and stop wasting yours.
The call to .loc. should have been in UPPER CASE i.e. .LOC.
In the call to ipcgive I should have explicitly defined a field to pass as
the fourth parm. (this is a flags field for which, according to the manual,
none are currently defined)
Anyway that how I got it to compile. Whether it works is another problem.