Tracking the big issues

This is a tracking issue only, not intended to propose any solutions, but merely to keep a record of big ideological discussions that need time and further discussion to be resolved into smaller, more implementable proposals. I will keep this updated as more turn up.

1. [Should individual IfcPropertySets or IFC properties get a GUID](https://forums.buildingsmart.org/t/bsdd-guids-at-the-field-property-level/362)
2. [Should finer grained classes and psets be introduced for parts of doors, windows, etc](https://forums.buildingsmart.org/t/ifcsill-development/879)
3. [Can IFC serialisations be referenced and instanced](https://forums.buildingsmart.org/t/how-do-i-include-and-instance-ifc-files-in-other-ifc-files/805)
4. [Landscape IFC needs a project in itself](https://forums.buildingsmart.org/t/what-ifc-class-should-i-put-turf-groundcovers-herbacious-vegetation-and-woody-trees/1197)
5. [Should documents have a GlobalId](https://forums.buildingsmart.org/t/ifcdocumentinformation-could-have-an-attribute-globalid/845)
6. [The documentation should clarify usecases for rooted relationships](https://forums.buildingsmart.org/t/the-non-permanent-guids/1059/4)
7. [Should relationships be merged and have GlobalId tracking optional](https://forums.buildingsmart.org/t/ifc-modernization-relationships/1462/17)
8. [There are potentially missing unit types](https://forums.buildingsmart.org/t/design-options-units-color/2006)
9. [How are design options supported](https://forums.buildingsmart.org/t/design-options-units-color/2006)
10. [Should there be psets for IT system security](https://forums.buildingsmart.org/t/extending-ifc-for-it-security/2183)
11. [Material categories should be reviewed with a dedicated team as well as relevant psets identified](https://github.com/buildingSMART/IFC4.3.x-development/issues/29)
12. [Qto quantity names are inconsistent in their naming of widths, height, length, depth, and thickness](https://forums.buildingsmart.org/t/when-is-a-door-not-a-door-choosing-the-correct-entity-classification-for-quantity-take-off/2857/5)
13. [Should there be an IfcColourLegend of sorts to show preset colours that represent property values as opposed to appearance](https://forums.buildingsmart.org/t/ifc-development-monthly-call-16-july-2020/2831/8)
14. [How should high polygon proxy objects be referenced](https://forums.buildingsmart.org/t/ifc-development-monthly-call-16-july-2020/2831/8)
15. [A full alignment with X3D and potentially new glTF PBR textures is required. Currently IFC only has partial support](https://github.com/buildingSMART/IFC4.3.x-development/issues/155)
16. [Should IFC ship computer parsable descriptions to aid vendors in providing documentation for users](https://forums.buildingsmart.org/t/where-can-i-find-computer-interpretable-descriptions-for-ifc4add2/919)
17. [There are too many ways to specify colours in IFC. Can they be simplified?](https://forums.buildingsmart.org/t/ifc-textures-and-colors-current-situation/2862)
18. [Should IFC store details about mappings to aid standardised migration between versions?](https://forums.buildingsmart.org/t/ifc2x3-to-ifc4-mappings/3093)
19. [Potentially a bunch of work to be done to support soil properties](https://forums.buildingsmart.org/t/defining-soil-properties-in-ifc-4-3/3102)
20. [Proposal for an "extends to" roof / wall relationship](https://forums.buildingsmart.org/t/csg-vs-ifcfeatureelement/2115)
21. [Proposal to merge the semantics of openings with CSG operations in the representation tree](https://forums.buildingsmart.org/t/csg-vs-ifcfeatureelement/2115)
22. [Proposal to define more situations of IfcConstraint (or another mechanism) on creating parametric geometry in IFC](https://forums.buildingsmart.org/t/a-small-step-to-parameterizing-ifc/3223)
23. [Proposal for IfcMaterial to be rooted](https://forums.buildingsmart.org/t/proposal-for-ifcmaterial-to-become-rooted/2721)
24. [A bunch of proposed upgrades to IfcRelSpaceBoundary](https://forums.buildingsmart.org/t/ifcrelspaceboundary/2709)
25. [Proposal for a 3D lattice grid object, potentially for modular design](https://forums.buildingsmart.org/t/request-add-support-for-3d-grid-parametric-in-all-ifc-versions-for-all-bim-software/3414)

Start by reviewing the linked forum discussions and related GitHub issues, which are the only research entry points named here. This issue is a record of unresolved ideological discussions rather than an implementation task, so no files, tests, proposed change, or concrete definition of done is identified.

Written by the indexing model from the issue text.