How do I find out practical information (lines, timetables, frequencies, maps, etc) about the SNCB network in the Bruxelles-Capitale region?

Various Brussels public transport tickets allow access to the SNCB network in the Bruxelles-Capitale region. By looking at the map provided by STIB, there are many SNCB lines and stations covered. How do I find out practical details for this network, such as timetables, frequencies, lines, and so on? I am only interested in the part inside the Bruxelles-Capitale region, since that is covered by the same tickets used with the local public transport. I could not find this information on the SNCB website.