%O – Promille - thousandth

[Gunther Schadow]

Claire Marie West (clairemwest) proposed in #69 to add

%O – Promille - thousandth

[Gunther Schadow]

interesting proposal if at all, I would say the o should be lower case "%o". BUT we already have [ppth] - parts per thousand, does it really matter to have a unit symbol for something rather trivial? I will propose rejection, with the invitation of someone else to support the case.

[Simon Cox]

Actually there is a proper symbol for this: ‰ It is sometimes used in geochemistry, particularly for isotopes. It is functionally the same as [ppth] but might be helpful for the symbol to be available somehow. Is it possible for the UCUM schema to support an alternative symbol?

[Simon Cox]

Also see ​https://en.wikipedia.org/wiki/Per_mille

[Christof Gessner]

This ticket touches on the question of connecting a "printable representation" to a UCUM (atomic) unit. Which raises a lot of question, including how to display UCUM expressions that are not atomic.

I tend to reject this, claiming this is out of scope for the UCUM code system. I saw a related ticket, addressing the question of µg vs ug.

Note that there is a liaison between ISO/TC 215 and ISO/TC 12 with the goal to establish a connection between UCUM and the ISO 80000 series. The latter addresses the question of "printable symbols", among others.

[Simon Cox]

Apologies for my earlier comment. I was confusing the issue. Yes there is a correct Unicode symbol for promille, but it is not available on a 7-bit ascii keyboard. UCUM codes are explicitly limited to 7-bit ascii keyboards.