I wrote a flight planning program for a B747-400 which faithfully emulates the flight planning/operations rules for international flights, called PS1FPLAN. The link below is a sample flight release for a US FAR 121 flight from JFK to JNB (Jo'berg South Africa). The flight is initially dispatched into Windhoek Namibia (FYWH), with a plan to redispatch the flight into JNB over ILDIR intersection.
The left column details the fuel requirements for the initial dispatch from JFK into WDH, using KMP (FYKT) as the alternate. 359900 lbs is the minimum fuel to launch to WDH using full 121 10% flag reserves. Launching out of JFK with 365000 on board brings JNB into range, with a 200NM Alternate (BFN/FABL).
The right column details the fuel requirements from the redispatch fix (ILDIR intersection) onto JNB. This column is ADVISORY ONLY, and is replaced with the actual redispatch release, issued no more than 2hours prior to the redispatch fix. In the advisory, 69.5 is the initially planned min fuel over ILDIR, and the flight planned fuel is 77.5 over ILDIR, giving 8.0 as contingency fuel over ILDIR.
Hope this helps!