Unfortunately, T-V hs been dropped in SPDX 3.0.
SPDX v3 is based on a graph model that can represent hierarchies natively. It can then be serialized in a file, for example, in JSON format.
Most SBOM use cases don‘t need the ability to put your detailed software architecture in the SBOM.
The whole idea is to use specific libraries to produce and consume SBOMs.
You wouldn't expect people to "manually create" JPG images, would you?
Unfortunately, T-V hs been dropped in SPDX 3.0.