How to UCUM express new MET units.

[ExOnc]

New metabolic equivalent (metabolic cost of physical activity) values have been published for older adults (age ≥60). The definition value for this new MET is 2.7. Definition unit is the same: mL/kg/min. The Compendium of Physical Activities shows two slightly different expressions of this: "MET60+" and also "MET60", both with subscripts for "60+" and "60".

What would be the c/s and c/i expression of this new metabolic equivalent for older adults: [MET_60+] or [MET_60]? Would the terminal "+" complicate machine readability? Can a greater than ">" be inserted after the underscore "_"? And if so, then "59" should be the age. Should year "a" also be included [MET_a>59] or is "a" only for calendar year (I do not see a UCUM for "age")?

Another possibility is: "[MET]{age >59}".

Thank you in advance.