In a dotnet-cli scaffolded Angular 4 project, the module artefact is divided into three files, one each for shared, server, and client and named as such: <modulename>.ts.shared, <modulename>.ts.server, and <modulename>.ts.client. In a mainstream, de facto, Angular application, we normally just have the one <modulename>.ts.
I have been able to guess, often correctly, what should go into which file. I have had good results already by just looking at the content of the module as 3 files in a dotnet-cli scaffolded project.
Yet I would still prefer to understand the pattern used to determine the content of each file. Then, indeed, I would very much like to learn how to start with 3 files from scratch.