how does k function behaves when the first argument is equal to

[Richard_Zwz]

Interfacing with Kdb+ from C( https://code.kx.com/trac/wiki/Cookbook/InterfacingWithC
) says: ... The k function is used to send messages over the
connection. If a positive handle is used then the call is synchronous
otherwise it is an asynchronous call. ..

What does this mean?
K r=k(0, "f", arg1, arg2, NULL); // handle = 0

thanks.

[charlie]

it behaves as a sync call, i.e. blocks until execution is complete