Below are abbreviations used in aviation, avionics, aerospace, and aeronautics.
CAT I Enhanced: Allows for lower minimums than CAT I in some cases to CAT 2 minimums CAT II: Operational performance Category II CAT IIIa: Operational performance Category IIIa CAT IIIb: Operational performance Category IIIb CAT IIIc: Operational performance Category IIIc Sources