Effective distance of Mamiya 7 viewfinder image?

Does anyone happen to know the apparent distance of the RF image? The information does not appear in my M7 owner manual. I recall hearing that some SLRs (don't recall which brand) are designed to ~1meter, but I've never heard about this in the context of rangefinders. Perhaps it's not relevant?

This is of interest to People Of A Certain Age who are considering the available diopter accessories.

I've never thought about this when using my Mamiya 7. At 53 perhaps my eyes are bad enough yet. Grin. Good question though.