the “value” of the field is what is used.
for example:
red : Red
the value is “red” the label is “Red”. As long as the value part stays the same then it does not matter what you change the label to or what order this value appears in. If you change the value part, then the value “red” becomes an invalid value and when you edit the page again this value will not be shown in the selections, and since it will not appear in the selections it cannot be selected even if that is the value for the field on that page.
