And if you follow that drawing, connect(for instance) input #1 of the diseqc switch to one of the "L" outputs of the LNB, and input #2 to one of the "C" outputs.
Then, in the receiver, for all your regular linear birds, program diseqc #1 input, and 10750 for the LO.
But, for NASA which is on 119º circular, you'd program diseqc #2 input and 11250 LO.
See the LNB for which connectors are "L" and which are "C".
You can use either "L", and either "C", whichever is more convenient.
In other applications, you might need both L or C connectors, but not for this discussion.
The diagram is intended to show a L port and a C port connected to the Diseqc switch. We were hoping nobody would actually look at their Invacom lnbf and notice the graphics screwup !
The reason it hasn't been corrected is that the diagram has been heavily circulated into other areas, and finding all of them would be a terrible job. Good catch, but don't think you're the first person who noticed the error.