If I specify circle(0px at 0px 0px), how should the computed value looks like after serialization?

In "3.2. Computed Values of Basic Shapes", the spec says:

A <position> value in circle() or ellipse() is computed as a pair of offsets (horizontal then vertical) from the top left origin, each given as a combination of an absolute length and a percentage.

It seems to me that means the value would be computed to something like circle(0px at calc(0px + 0%) calc(0px + 0%)), and eventually serialized in this form.

This matches Gecko's current implementation, and I do think having the computed value in a most general form makes sense, but I'm not completely sure whether this is the desired result.

I'm confused because the section "3.3. Serialization of Basic Shapes" states

avoiding calc() expressions where possible, avoiding calc() transformations

but I guess that wouldn't change the result of serialization of computed value, as the computed value has already been in a form with calc(). Is that correct?