| unit | names the unit used for the measurement 
                                 
                                    | Status | Optional |  
                                    | Datatype |  |  
                                    | Suggested values include: | 
                                          cm(centimetres) mm(millimetres) in(inches) lineslines of textchars(characters) characters of text |  | 
                        
                           | quantity | specifies the length in the units specified | 
                        
                           | extent | indicates the size of the object concerned using a project-specific vocabulary combining
                              quantity and units in a single string of words. 
                                 
                                    | Status | Optional |  
                                    | Datatype | 1–∞ occurrences of 
                                       separated by whitespace |  
                                    | Values | any measurement phrase, e.g. 25 letters, 2 × 3
                                          inches. |  
                                    | <gap extent="5 words"/><height extent="2 ft 8 in"/>
 |  | 
                        
                           | precision | characterizes the precision of the values specified by the other attributes. | 
                        
                           | scope | where the measurement summarizes more than one observation, specifies the applicability
                              of this measurement. 
                                 
                                    | Status | Optional |  
                                    | Datatype |  |  
                                    | Sample values include: | 
                                          allmeasurement applies to all instances.mostmeasurement applies to most of the instances inspected.rangemeasurement applies to only the specified range of instances. |  |