A predefined value for a product characteristic, e.g. the the power cord plug type "US" or the garment sizes "S", "M", "L", and "XL" This ordering relation for qualitative values indicates that the subject is equal to the object. This ordering relation for qualitative values indicates that the subject is greater than the object. This ordering relation for qualitative values indicates that the subject is greater than or equal to the object. This ordering relation for qualitative values indicates that the subject is lesser than the object. This ordering relation for qualitative values indicates that the subject is lesser than or equal to the object. This ordering relation for qualitative values indicates that the subject is not equal to the object. A pointer to a secondary value that provides additional information on the original value, e.g. a reference temperature.