‘Semantic technologies’ are touted as the next big wave in Educational Technology and as the solution to many problems in this arena. Interdisciplinary work between the fields of Knowledge Management (KM) and Educational Technology (ET) is booming. But the crop of actual systems and semantically enhanced learning objects is still meager, maybe KM and EL they are lacking a consensus on the underlying notions e.g. of ‘semantics’, yielding specific problems in their interplay. In this paper we take a look at (...) semantic educational technologies and draw conclusions for their approach in KM. In particular, we (re)-evaluate the notions of ‘semantics’, ‘knowledge’, ‘learning’, their role for learning materials in ET, and how they interact with the contexts involved in the learning/teaching process. Based on this, we distill a list of conditions the underlying knowledge representation format must fulfil to support these. As these conditions are still rather abstract, we show how they can be realized in a concrete language design, taking in our OMDoc (Open Mathematical Documents) format as a point of departure. (shrink)