| Name | Kind | Description |
| YawChangeValue | class instance | A rate of change of angle of rotation of a thing about its normal axis, measured in degrees per second. |
| YawValue | class instance | An angle of rotation of a thing about its normal axis, relative to its direction of motion, measured in degrees; negative values indicate rotation to the left. |
| YDescriptionText | class instance | A description of the second dimension's data. |
| YearDate | class instance | A year. |
| YearMonthDate | class instance | A year and month. |
| YValue | class instance | A value (and optionally, the 1-sigma absolute uncertainty of this value), of the second dimension of an equation. |