Encoded

Here the preposition serves to relate two entities, a number of books and a table. The relation encoded by the preposition is a spatial one; one entity is located on the top surface of the other. It is easy to come up with other similar examples, where this concrete, spatial relation is encoded by on. A great many abstract uses of prepositions, may, in fact, be traced back to a concrete, spatial relation. Consider the following examples, where the prepositions are all used to encode temporal relations which can be derived from spatial ones):

http://awelu.srv.lu.se/grammar-and-words/selective-mini-grammar/prepositions-and-prepositional-phrases/

What is the meaning of "encoded" here?

Thanks