These are Banverket's tracks in central Stockholm, and the pendeltåg line to Nynäshamn.
The idea was that this map would cover exactly "Stockholms ställverksområde" (an "interlocking area" where all signals and switches are controlled from Stockholm C) plus the Nynäshamn branch. This didn't quite work out, because I misremembered just where the limits of the ställverksområde are. According to that principle, this map ought to include Sundbyberg (which is now at map 'Bål') but not the platforms at Stuvsta.
The platforms shown in cyan on the map are for the pendeltåg service, a commuter rail system run for the Stockholm transit authority by a company separate from SJ. The pendeltåg platforms are generally access controlled, though this principle is not followed for the little-used stations in the outer end of the Nynäshamn branch.
As of this writing I still have some hope of getting a more complete picture of the freight stations at Älvsjö (possibly including parts of the Liljeholmen area), Tomteboda and Stockholm N. I might also be able to extend the level of detail for the pendeltåg depot at Älvsjö, but the rest of the Hagalund coach depot is so inaccessible that I've given up hopes on that.
There is something interesting going on to the southeast of the platforms at Stockholm S, but it goes on inside a tunnel, and it is not easy to see exactly what it is. City maps show a long track along the south coast of Södermalm emerging from a tunnel some distance form the station. The outer end of this track passes under the Green Line metro bridge between stations Skanstull and Gullmarsplan, but I have not followed up on it in detail.