I am making a modpack where planets may be added etc. But each planet needs to have a static structure spawn in it.

I cannot use the type=xyz since there are other planets that shouldn't have this structure.

Essentially, I tried this: id<=100 & id<=300 & !(id%2); grab all dimensions where the ID is greater than or equal to 100, but less than 300, and must be an even number. Such that it'll generate the structure in dimensions: 100, 102, 104, 106... until 300.

Is this possible, or should it be implemented?

Hrm... I see the use-case, but comparing IDs with integer expressions seems very hacky. I think the best solution would be defining dimension types for the specific dimensions using the dimension dictionary, and putting sensible values that help determine where structures should spawn. Have you figured anything out? I realize this issue has been created quite a while back.