Creating a full circle with one arc command

I just found out, that it is not possible to create an arc which does a
full circle. I was wondering if this is somewhere written in the
specification so I searched and found this:

> If the endpoints (x1, y1) and (x2, y2) are identical, then this is
equivalent to omitting the elliptical arc segment entirely.

(https://www.w3.org/TR/SVG11/implnote.html#ArcImplementationNotes F.6.2
Out-of-range parameters)

I was wondering why this was added to the specification. For me it makes
totally sense to have a full circle when the largeArcFlag is set to 1. The
maths in (F.6.5 Conversion from endpoint to center parameterization) breaks
of course but it does so already when you have a radius of 0 which is
already allowed.

Beside the maths everything still makes sense.

So what were the reasons to disallow a full circle and what are the chances
to change this chapter in the specification (at least for SVG2)?



Best regards,
Ulrich-Matthias Schäfer
(maintainer of svg.js and svgdom)