If that is the bit around your 10km mark then I know the area well. In eastern states there's consideration to just map rubbish like that as yellow.
Got it in one. I'd go with the yellow (as in rough - very rough - open) idea wholeheartedly - I couldn't see how I could make any sense of it with tracks. I rode down what I thought was a boundary track but turned out to be the watercourse. Useless for control sites and how you'd get through it would depend on whether it was wet or dry. Best I can do is try and get the entry and exit tracks right.
I've ridden that watercourse before when setting for the 6hr rogaine a few years back. Goes from track to watercourse back to track then ends nowhere.
Use open were you are allowed to ride and rough open where not, regardless of the terrain.
Thanks - didn't realise the "opens" had different rules
We're trying to standardise across Aus to make it less confusing but doesn't always happen. I've ridden two events in the same carnival before where pale yellow meant able to be ridden on one map but not on another. Kind of sucks when you plan route choices that you then can't take due to the vegetation that you only discover when you get there.