In our guidelines, we have written the following:
"Units are identifiers. For example meter <mi mathvariant="normal">mor second<mi mathvariant="normal">s</mi>. When units are written using multiple letters, they should be marked up as a single element: <mi>Nm</mi>. Depending on the layout of the unit, you have to use other MathML elements to mark up a single unit such as metre per second squared:"
Would it be more correct to say that prefixed units should be marked up in one <mi> element, while compound units should be in multiple <mi> elements.
"nano meter": <mi>nm</mi>
"newton meter": <mi>N</mi><mi>m</mi>
In our guidelines, we have written the following:
"Units are identifiers. For example meter
<mimathvariant="normal">mor second<mimathvariant="normal">s</mi>.When units are written using multiple letters, they should be marked up as a single element:<mi>Nm</mi>.Depending on the layout of the unit, you have to use other MathML elements to mark up a single unit such as metre per second squared:"Would it be more correct to say that prefixed units should be marked up in one
<mi>element, while compound units should be in multiple<mi>elements."nano meter":
<mi>nm</mi>"newton meter":
<mi>N</mi><mi>m</mi>