mseo:CrossSection might be a subclass of bfo:site instead of bfo:spatialRegion

[Lenostatos]

The Current State

In MSEO, cross section is currently a subclass of bfo:spatialRegion. I believe that cross section might be a subclass of bfo:site instead.

Currently: cross section =def. a surface or shape exposed by making a straight cut through something, ...

What the BFO Book (2015) Says on the Matter

Regarding the differences between bfo:spatialRegion and bfo:site I did not find the BFO definitions as helpful (but I have copy-pasted them below for reference). Let me instead cite some sentences from the 2015 BFO book which are more clear IMO:

page 112+; Section "BFO: Site"

A site exists because there is some material entity in relation to which it is defined, [...].
[...]
Every site will at any given moment coincide with some spatial region. But the site is not identical with the spatial region with which it coincides, because the site but not the spatial region is ontologically (site-) dependent upon its retainer. In the case of mobile sites (e.g. a ship's cargo hold) the site in question will cycle through a continuous multiplicity of spatial regions as its retainer, the ship, moves. [...] Spatial regions cannot move since it is spatial regions in and through which movement occurs.

page 113; Section "BFO: Spatial Region [...]"

A spatial region is a continuant entity that is a part of space (by which we mean: a part of the maximal or total space, or in other words of the whole of space). Both material and immaterial entities occupy regions of space; processes occur in space. When an object moves from one place to another, then it occupies a continuous series of different three-dimensional spatial regions at different times.

My Opinion/Suggestion

Regarding the definition of mseo:crossSection: Is the cross section relative to the "something", i.e. does it move together with the "something"? Or is it relative to the whole of space, i.e. does the cross section stay at the earth coordinates where the act of cutting took place, even when the "something" is moved somewhere else?

To me, the definition sounds as if the first option is meant. If that is correct, I believe that bfo:site is the most fitting super-class for mseo:crossSection because of the elucidations on bfo:site and bfo:spatialRegion cited above.

Definitions in BFO 2.0 and BFO 2020

spatial region

• BFO 2.0
  • elucidation: A spatial region is a continuant entity that is a continuant_part_of spaceR as defined relative to some frame R. (axiom label in BFO2 Reference: [035-001])
• BFO 2020
  • elucidation: A spatial region is a continuant entity that is a continuant part of the spatial projection of a portion of spacetime at a given time
  • examples: An edge of a cube-shaped portion of space, a line connecting two points, two parallel lines extended in space. A cube-shaped region of space, a sphere-shaped region of space, the region of space occupied by all and only the planets in the solar system at some point in time. The surface of a sphere-shaped part of space, an infinitely thin plane in space. The spatial region occupied at some time instant by the North Pole.

site

• BFO 2.0
  • elucidation: b is a site means: b is a three-dimensional immaterial entity whose boundaries either (1) (partially or wholly) coincide with the boundaries of one or more material entities or (2) have locations determined in relation to some material entity
• BFO 2020
  • elucidation: <same as BFO 2.0>
  • examples: A hole in a portion of cheese, a rabbit hole, the Grand Canyon, the Piazza San Marco, the kangaroo-joey-containing hole of a kangaroo pouch, your left nostril (a fiat part - the opening - of your left nasal cavity), the lumen of your gut, the hold of a ship, the interior of the trunk of your car, hole in an engineered floor joist; An air traffic control region of type A is determined in terms of elevation above mean sea level of lower and upper boundaries.