[1.19 RFC] Change tag convention to hierachical (for example `c:ores/tin`)

This issue is to start some discussion about possibly changing the tag convention used by the ecosystem. I am opening this on Fabric so that the discussion can be public, but the major mods that are concerned are AE2 and MI (myself), Create (@AlphaMode), IR (@NotSteven) and TR (@modmuss50), and if we all decide to change convention then the rest of the ecosystem will be forced to adjust.

The idea would be to adopt Forge’s convention for tags, but with the c: namespace. So that would be c:ores, c:ores/tin, c:nuggets/copper, etc…

Advantages

• Hierarchical organization. Feels a lot cleaner, especially for people looking into mod jars. Shouldn’t matter for mod devs since tags should really be generated via datagen and not written manually.
• Easier multi-platform mods. They would only need to change forge: to c:, but the paths for standard tags could stay the same.

Disadvantages

• Doesn’t match the standards established by Mojang. Can be argued that it doesn’t matter since this is not vanilla.
• Would require a lot of work to update, which makes this possibly not worth it.

[Juuxel]

I’m against this change.

• The current “flat” tag system has been widely used for multiple MC versions without any real issues. Most mods won’t have so many tags that it’s hard to browse the tag list. Mods with that many will most likely generate them and not touch them by hand at all.
• It’s also quite widely adopted by mods that aren’t one of the large tech mods mentioned - even simple mods like Adorn might use tags like c:wooden_chests - that would be changed by this move - pretty widely in recipes.
• It might be a bit confusing to have e.g. c:ores/tin but minecraft:iron_ores - we should match the vanilla convention where there’s a clear one like with ores.
• Multiplatform mods have to change the ids anyway, so change of namespace vs change of file name is not that much different. (Especially if mods generate the tags like you recommend)
• We don’t need to copy-paste Forge’s decisions for the sake of matching Forge.

[liach]

Imo a tag unification system, where two ids, such as c:tin_ores and forge:ores/tin can be merged to refer to the same tag (instead of one contained in the other), would be a better solution.