The following is for guidance only. This is not a call, but simply how the umpires see the various calls applying. Hope this helps.
Rules/Calls/Definitions that apply.
RRS 18.2(c)(2) ” if she becomes overlapped inside the boat entitled to mark-room she shall also give that boat room to sail her proper course while they remain overlapped.”
This rule always applies.
Definition of room and mark room
Team Race Call J7 and Match Race Call K4
In all cases Yellow arrived at the zone clear ahead of Blue.
Zone A blue must give Yellow room to sail to the bow of the RC boat. All risk is on Blue.
Zone B more complicated. The gybe line as drawn is a proper course for Yellow to sail, so if Blue is overlapped to leeward of Yellow she must allow Yellow room to gybe to sail to the port quarter of the RC boat. If Yellow after gybing (onto port) sails above this course she will not be exonerated under rule 21. If Blue gybes inside Yellow, Blue in not entitled to mark room. This is a slightly grey area for calling as it requires a view from the umpires as to where the gybe line is.
Zone C both boats are past the gybe line and have not left the zone. If the line is port biased then Yellow’s proper course is not to gybe, so if she does she is not exonerated under RRS 21 and risks a penalty. If the finish line is starboard biased then a proper course is to gybe. So quite risky for Yellow.
If both boats gybe in Zone C then TR Call J7 applies.