The unit of measure that applies to the Item price base quantity, must be the same as the unit code of the Invoiced/credited quantity. Codes for unit of packaging from UNECE Recommendation No. 21 can be used in accordance with the descriptions in the "Intro" section of UN/ECE Recommendation 20, Revision 11 (2015): The 2 character alphanumeric code values in UNECE Recommendation 21 shall be used. To avoid duplication with existing code values in UNECE Recommendation No. 20, each code value from UNECE Recommendation 21 shall be prefixed with an “X”, resulting in a 3 alphanumeric code when used as a unit of measure.

Usage
Optional
Example value
C62
Code lists
Recommendation 20, including Recommendation 21 codes - prefixed with X (UN/ECE), Recommandation 21 (UN/ECE)
Rules
Identifier/Error message Flag
EHF-REMINDER-B19501
Value MUST be part of code list 'Recommendation 20, including Recommendation 21 codes - prefixed with X (UN/ECE)' or 'Recommandation 21 (UN/ECE)'.
fatal