The DEMAND knowledge network (also a learning community) consists of an varied, lightly organized bunch of people who join in lining up, exploring and thinking about problems and solutions within the DEMAND scope and themes (Data Engineering and Data Management, and also AI Engineering). To support this and also to create (public) content, we structure the knowledge platform (basically a Wiki combined with a knowledge graph) by presenting Problems and Solutions (also called Tools: a Toolbox) and how these are related. We will also include Cases: examples of how specific (combinations of) solutions solve (combinations of) problems. This is all very much a work in progress.