Hi,

The idea of tags for blocks used in multi block is having a way to easily filtered them with a mod like JEI.
For example, i'm building the crusher so with JEI I type in the search field $ie_crusher_mb (which stands for "Immersive Engineering Crusher Multi Block").
Adding the "ie_" at the start of the tag is because JEI doesn't like search like $forge:ore. We can only search $ore
Then with that filter, I'd find:

• Steel Scaffolding
• Light engineering block
• Redstone engineering block
• Steel fence
• Hopper

Thanks you.
Have a great day.

Well the manual does provide you with a list of all the blocks you need...

Yes I know that 😄
But, the benefit would be to be able to pin the required items more easily than opening the book then search in JEI and then look for the next block in the book and search it in JEI and so on.
I know it sounds lazy 😅

You can already view multibocks in JEI with another mod so you can pin the blocks.

https://www.curseforge.com/minecraft/mc-mods/just-enough-immersive-multiblocks