Emoji support is probably the best way to demonstrate what I mean:
A simple example: if this (🐦⬛) renders as an image of a blackbird, your system supports Unicode 15.0.
A more complex example: if this (🧑⚖️) appears as a judge, your system supports Unicode 12.1, if it appears as a Person followed by Scales your system supports Unicode 10.0, and if you can only see the Scales, your system supports Unicode 4.1.
The downstream use case would be to avoid attempting to output specific characters for a user that wouldn’t see them correctly (i.e. if I want to output a blackbird, I want them to see it, or if I output a judge I don’t want them to see scales).
Emoji support is probably the best way to demonstrate what I mean:
A simple example: if this (🐦⬛) renders as an image of a blackbird, your system supports Unicode 15.0.
A more complex example: if this (🧑⚖️) appears as a judge, your system supports Unicode 12.1, if it appears as a Person followed by Scales your system supports Unicode 10.0, and if you can only see the Scales, your system supports Unicode 4.1.
The downstream use case would be to avoid attempting to output specific characters for a user that wouldn’t see them correctly (i.e. if I want to output a blackbird, I want them to see it, or if I output a judge I don’t want them to see scales).