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. If your using this with Wordle, only put it here if its shown as yellow, otherwise out it into the Exclude box lower.
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.
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.