The procedure below shows four procedures and two junctions, linked together. The procedure shows that following on from the procedure "look at last years report" there is a junction with the symbol X in it. In IDEF3 terms this means it is an exclusive or (XOR) junction. At this point there are two alternative paths, namely "update last years report" or "create a brand new report". This junction is referred to in IDEF3 terms as a fan-out XOR junction, that it is an XOR junction into which one link goes, but more than one link leaves. Following on from the two succeeding procedures, there is another junction with the symbol X in it -- this is a fan-in XOR junction (a XOR junction into which more than one link enters but only one link leaves) -- and then there is another procedure "print out report". Translating this procedure into English gives "first look at last years' report, then either update it, or create a new report and then print out the report".
The other junction types are And (its symbol is &), which means that all of the succeeding or preceding Links can be followed, or Or (its symbol is O), which in English means one or more succeeding or preceding Links can be followed. Exclusive or (XOR) is more akin to the normal English use of the word "or", meaning only one link can be followed, whilst the IDEF3 term Or, as used in the procedure builder, means that one or more of the succeeding or preceding links can be followed.
Finally, for IDEF3 modellers, it should be noted that Procedure Builder does not discriminate between asynchronous or synchronous junctions types. What this means is that the Procedure Builder does not specify the relative timings of the procedure paths that either converge to or diverge from a junction. This means that there are no timing constraints on the completion of the procedures before a junction, or the start of procedures after a junction.
