[GVIrish]

SCIFs are for viewing TS materials, whether or not they are SCI. Even then, SCIFs are often employed for processing things that are only marked Secret or systems only handling Secret. But yes, if we want to be specific, Secret has a lower bar and can be worked on outside of SCIFs but still not in public or at home.

[bobtheborg]

Again, no. Not all TS material is SCI. You only need a SCIF for SCI.

"SCIFs are often employed for processing things that are only marked Secret or systems only handling Secret"

No. SCIFs are expensive. They are not built when they are not needed. They are only needed for SCI materials.

[GVIrish]

That hasn't been my experience over 20 years. I've worked in multiple SCIFS that didn't handle SCI at all.