Content consists of explanations, examples and definitions of concepts used in learning environments, representing different aspects of the concept in question. It may also consist of physical or digital resources that have a representation in the system for lexical purposes. So the definition of content consists of two parts:
Designing a representation of a piece of content in the system. This must include meta-data on the content, such as type information, and the location of digital content or the identification of physical content. The idea is that you should be able to search for and choose content without having seen the content itself, only this description.
Associating such a content description with a concept or other type of neuron.
The ideas for the usage of content and aspects are carefully described in [cid52], and will therefore not be repeated here.