Is: The letter at that position. Note "Is Not" is ignored for that row.
Is Not: The letter is not one those, but they are in the word somewhere else.
Include: The letters here are somewhere in the word, the 'Is Not' letters are added to this. If a letter is here twice then two of those letters must be in the word. Note since the 'Is Not' letters are added to this, if you have a letter in a 'Is Not' field and here then there must be two of those letters.
Exclude: These letters must not be in the word. If a letter is in the 'Is' field for a given position but also included here, then the letter is still
in the position where the 'Is' field says it is, but nowhere else.