Ok yes, I meant to say that the “how TfL calculates statuses” (aka CSL2) in in the public domain: Homepage - MTREL
CSL2 is an industry wide sign that a TOC is experiencing severe service disruption and customers may require access to alternative routes. It must be noted that CSL2 can be declared outside of severe delays if there is a benefit to the customer.
The code is part of the https://nr.whoosh.media/app/auto but there are people much better at CSS than me that are still to work on the look so this bit of code hasn’t get rolled out to the live systems.