I've tried to sensibly sort these out, but I wanted to make sure it was noted that these can all be confused.
The first problem is with grouping basic units and deciding what is a real unit. QUDT calls many events their own units. (ie, measuring in units of "breaths" or "flights") I think those shouldn't be real units and the unit should be "event" and the variable name should be "breaths."
The second problem is in compound derived unit types. For example "inverse length" for units with a dimensionless quantity over length like wavenumbers, "amount of substance per length" for units of numeric linear density like typographers points per inch, and "radioactivity per volume" for units dealing with radiation, which is itself dimensionless.
I've tried to sensibly sort these out, but I wanted to make sure it was noted that these can all be confused.
The first problem is with grouping basic units and deciding what is a real unit. QUDT calls many events their own units. (ie, measuring in units of "breaths" or "flights") I think those shouldn't be real units and the unit should be "event" and the variable name should be "breaths."
The second problem is in compound derived unit types. For example "inverse length" for units with a dimensionless quantity over length like wavenumbers, "amount of substance per length" for units of numeric linear density like typographers points per inch, and "radioactivity per volume" for units dealing with radiation, which is itself dimensionless.