You may be looking for dimensions in some engineering product drawings and seeing unusual specifications. Sometimes, there may be the abbreviation “REF” at the end of dimension values. This dimension or note prior to the REF is given a reference only and not the actual value. Thus this REF dimension should not use as a part acceptance criterion.
For example, the 08150 finger guard from Qualtek datasheet shows that the height is 5.9 REF. This guard height is a reference.
