As mentioned in this discussion. This historically has been out of scope for UCUM. From §14 of the specification:
If unit symbols for the purpose of display and print are derived from The Unified Code for Units of Measure units, the square brackets can be removed. However, display units are out of scope of The Unified Code for Units of Measure.
This topic should be discussed at a future UCUM Committee meeting. This would provide additional value to UCUM and aid implementors.
As mentioned in this discussion. This historically has been out of scope for UCUM. From §14 of the specification:
This topic should be discussed at a future UCUM Committee meeting. This would provide additional value to UCUM and aid implementors.