To add to what Jack said, there are also a whole host of alternative fingerings. Most notes have more than one fingering and these can be useful in a number of ways. Individual Recorders do vary and slight adjustments to fingering are sometimes needed to bring particular notes into tune. A number of alternative fingerings are genuine alternatives. Second octave E on the descant/tenor (A on a treble or bass recorder) is the best example as it can be fingered in three different ways all of which are in tune. Other alternative fingerings are slightly sharp or flat relative to the standard fingering which can be useful if you want a loud or soft dynamic. Many standard trill fingerings are slightly off in one or other of the notes because they only involve moving one finger so a more rapid alternation is possible and the notes pass so quickly that most do not notice they are slightly out of tune. A similar consideration applies to decoration of traditional music. I do a B roll on a descant by briefly flicking my thumb off the thumb whole and then tapping with the A finger. I find using the thumb lets me keep better control of the instrument.

There's a very nifty utility for recorder fingerings available for download here. The fingerings are given on a little recorder picture and there is an indication of standard fingerings, trill fingerings, and whether a particular alternative is sharp or flat.

The Dolmetsch materials on the recorder and on music theory in general are still there. Just click here