Here is a list of all enums with links to the classes they belong to:

- u -

• UnaryOperator : QgsExpressionNodeUnaryOperator, QgsSQLStatement
• UndoCommand : QgsLayout, QgsLayoutItem, QgsLayoutItemPage, QgsLayoutMultiFrame
• UnitType : QgsTolerance, QgsUnitTypes
• UnplacedLabelVisibility : Qgis
• UpsideDownLabelHandling : Qgis