scRGB = (linear) RGB in HDRI mode?

[NicolasRobidoux]

It appears to me that HDRI mode may make the RGB color space match the spec of the scRGB color space, color space which is gaining quite a bit of traction, deservedly so: floating point ("infinite gamut") RGB with sRGB primaries makes tons of sense as a work space.
Putting something to this effect in the documentation may be a good thing. (Assuming that I'm right: I've not actually checked.)
scRGB is explicitly supported in the GEGL and VIPS libraries, for example. Actually, the linear color space of choice for GEGL is scRGB (I had nothing to do with this decision, which I am pretty sure predates Microsoft's introduction of scRGB).
(Of course, color space issues is a rat's nest. So, one could also argue that making the link explicit in the documentation is inviting trouble, unless things are very carefully matched for all quantum, for example.)

[magick]

It appears that scRGB is linear RGB without clamping which as you surmised is already supported under the HDRI release of ImageMagick. The normalized values of scRGB range from -0.5 to 7.49999. Where 0.0 is black and 1.0 is white.