Gajan,

The airlines we handle or have worked for, yes they had manuals for that.
Passenger & Station Handling Manual.


yes, if you are travelling your own airline, it is about seniority and staff level. You are able to see it in the endorsement box. Or at the gate computer, depends what system they use to clear waitlist etc.
It should be that way. As you see it does not happen always that way, not only with KLM.


for example, ZED can be issued for Y or C class (KL issues paper tickets).
ZED are normally issued when travelling on other airline then your own.
KLM travelling department issues them M/C which means Y class other carriers C class on KLM flights if space available. The reason why they do this is because for example an TAP flight to Lisbon leaves at 12.35pm, if they are not able to get on this one, they still have time to catch the KL flight to Lisbon at 13.25pm.

To anwers your 1st question, some airlines are using very strict manuals/documents.
If you ZED fare is Y class, you travel Y class, means you cannot be upgraded at all.


Worked for an airline, always issued my tickets (handling agent)in Business class, if cabin was full could be downgraded to Y, they would not upgrade you from Y to C. Never.
If I flew Y class, was still able to get refund for fare difference paid.


Even today, we handle airlines that will not upgrade you to C if your ticket shows only Y.


dutch_122