Tuning Capacitor

Im going to use this Tuning Capacitor for a project of mine, but im not sure how to wire it up, to get the capacitance is it C3 to negative asuch or is it c3 to C4?

heres the PDF link:
**broken link removed**

and the actual Capacitor
**broken link removed**

how do you wire this up as a capacitor in a ossiclator circuit?

It's not completely clear from the drawings but I believe each of the four capacitances are from each respective terminal to the common (ground) terminal.

ok, thank you verymuch