Reason for discrepancy in cube map axis labels

[ReignOfError]

When cube map images are rendered from the Reflect/Refract map (using the "Pick Object and Render Maps" button), each resulting image is given a suffix indicating which direction's view it depicts. For the front, back, up, and down images, these labels are assigned such that the perspective is of a camera/viewer inside the object looking out. For example, the front image (the one with the _FR suffix) depicts whatever is in front of the object from the perspective of the object's pivot point.

However, the left (_LF) and right images (_RT) contain the view in the opposite direction (i.e., the left image shows the view looking to the right and vice versa). There's an example cube map that demonstrates this on this page; I've embedded it below (note which edges of the _LF and _RF images contain the orange glow of the sunrise).

I'm curious about the origin of this convention. I asked about it recently on gamedev.stackexchange; one hypothesis was that the images are labelled from the perspective of a viewer facing the object for which map images are being rendered (thus what the viewer considers to be the left side of the object is the object's right side from its own point of view). This is plausible, but strikes me as a bit odd given the description in the documentation for the Reflect/Refract map (emphasis added, of course):

"This map works by using six renderings in the form of a cube that surrounds the objects. Reflect/Refract views the cubic maps from the perspective of the pivot point of the object, mapping them onto the object's surface as a spherical reflection map."

Since the rendering is performed from the pivot point, labelling the images from the POV of a viewer external to the object seems a counter-intuitive choice.

Any information would be appreciated (particularly from developers or anyone familiar with the "official" reason for this choice of convention).