I have seen the following type of phrase in various academic articles and books.
- Another important decomposition used in the sequel is the ...
- In the sequel, we identify the position ...
- the vector v (introduced in the sequel) must be considered...
At first, this use of "in the sequel" seemed strange, and I chalked it up to non-native English writing. I would say something like "in the following" or "below" in a case like this. However, I've seen it enough that I'm starting to question whether it's acceptable/standard English or not.
I can see an argument that by the etymology of the word, it can be used in this fashion. The modern definition of sequel applies to books, films, and events. What's the verdict?