The flat positions are named and numbered according to a progression counterclockwise around the circle of fifths. 1st flat is identical to 12th position. Similarly, 2nd flat is identical to 11th position, etc. There is a natural mode associated with each position. Here are the natural modes associated with some common positions.
First position is a major scale.
The mode name for the major scale is called Ionian . Second position is a major scale variant with a flatted 7th. The mode is called Mixolydian . Third position is a minor scale. There is more than one minor scale, and the mode for this one is called Dorian .