RelationalOperator defines the restricted set of operators that may be specified alongside numerical quantities in ICAO Annex 3/WMO No. 49.<br/><br/>These operators are used in cases where a precise value is not measurable, not precisely known due to measurement limitations, or not reported due to reporting restrictions.<br/><br/>For example, the "above" operator in conjunction with the reported quantity 10.6 indicates that the actual physical quantity is above 10.6 (at least 10.6).<br/>