All music sheets on this site includes fingering markings which are kind of tablature marks. They tell should the flute end to be closed (fully or partly) or left open. Here is a reading guide for fingering markings:

When a tone demands a partly closed fingering position e.g. half closed, it demands more accuracy from the hand and the ears. Different flutes may require slightly different way to cover the flute end partly. Finally your ears tell you when the tone has wanted frequency. When the aim is to close 3/4 of the flute end it becomes even more challenging. By repeating the exercises which include these closing technics it will become easier to get the wanted tones in tune.

© Janne Ojajärvi