8.11.6.2 IfcCorrectUnitAssignment（正确单位分配）
8.11.6.2.1 语义定义（Semantic definition）
如果 IfcUnitAssignment 中的 Units 集合仅包含具有不同 UnitType 的单元（适用于 IfcNamedUnit 和 IfcDerivedUnit），且最多包含一个 IfcMonetaryUnit，则该函数返回 true。
参数定义： Units : （输入）IfcUnit 的集合。
8.11.6.2.2 形式化表示（Formal representation）
FUNCTION IfcCorrectUnitAssignment
(Units : SET [1:?] OF IfcUnit)
: LOGICAL;
LOCAL
NamedUnitNumber : INTEGER := 0;
DerivedUnitNumber : INTEGER := 0;
MonetaryUnitNumber : INTEGER := 0;
NamedUnitNames : SET OF IfcUnitEnum := [];
DerivedUnitNames : SET OF IfcDerivedUnitEnum := [];
END_LOCAL;
NamedUnitNumber := SIZEOF(QUERY(temp <* Units | ('IFC4X3_DEV_62887e3f.IFCNAMEDUNIT' IN TYPEOF(temp)) AND NOT(temp\IfcNamedUnit.UnitType = IfcUnitEnum.USERDEFINED)));
DerivedUnitNumber := SIZEOF(QUERY(temp <* Units | ('IFC4X3_DEV_62887e3f.IFCDERIVEDUNIT' IN TYPEOF(temp)) AND NOT(temp\IfcDerivedUnit.UnitType = IfcDerivedUnitEnum.USERDEFINED)));
MonetaryUnitNumber := SIZEOF(QUERY(temp <* Units | 'IFC4X3_DEV_62887e3f.IFCMONETARYUNIT' IN TYPEOF(temp)));
REPEAT i := 1 TO SIZEOF(Units);
IF (('IFC4X3_DEV_62887e3f.IFCNAMEDUNIT' IN TYPEOF(Units[i])) AND NOT(Units[i]\IfcNamedUnit.UnitType = IfcUnitEnum.USERDEFINED)) THEN
NamedUnitNames := NamedUnitNames + Units[i]\IfcNamedUnit.UnitType;
END_IF;
IF (('IFC4X3_DEV_62887e3f.IFCDERIVEDUNIT' IN TYPEOF(Units[i])) AND NOT(Units[i]\IfcDerivedUnit.UnitType = IfcDerivedUnitEnum.USERDEFINED)) THEN
DerivedUnitNames := DerivedUnitNames + Units[i]\IfcDerivedUnit.UnitType;
END_IF;
END_REPEAT;
RETURN((SIZEOF(NamedUnitNames) = NamedUnitNumber) AND (SIZEOF(DerivedUnitNames) = DerivedUnitNumber) AND (MonetaryUnitNumber <= 1));
END_FUNCTION;