Abbas: Not clear on the word "flexible"

Yesterday the 15th summit of non-aligned nations started in Sharm al-Sheikh, and Mahmoud Abbas spoke to the assembled delegates.

He said, "We are for serious negotiations; we know that they will be hard and complicated. We will need your support, yet, flexibility on our side never means concession of our national principles. There will be no solution without Jerusalem, refugees and all final status issues."

So what, exactly, is he being "flexible" on? Not on land, not on Jerusalem, not on refugees; so where is this flexibility?

And why, exactly, does a Palestinian Arab state require Jerusalem to be its capital in order to exist?

And why, exactly, does such a state require its neighboring country to take in millions of citizens it claims as its own?

Perhaps the flexibility is in the timeframe for Israel to negotiate its own destruction.