If this were attached to a noun like "units" (e.g. Munits, like Mb in Megabits) I'd think the SI was a reasonable place from which to draw guidance. But it's a

If this were attached to a noun like "units" (e.g. Munits, like Mb in Megabits) I'd think the SI was a reasonable place from which to draw guidance. But it's attached to the number which to my eye seems like the accounting/finance Roman Numeral style would be expected. Thinking about it more maybe the MM should only mean million when there's a dollar sign. I'm not so confident anymore.