(In current parlance, we would most naturally think of this as a path from the root of a trie to one of its terminals, inquiring of each node its associated one-letter entropy, based on the continuations from that node.)
the central idea of minimum description length analysis (Rissanen 1989) is composed of four parts: first, a model of a set of data assigns a probability distribution to the sample space from which the data is assumed to be drawn; second, the model can then be used to assign a compressed length to the data, using familiar information-theoretic notions; third, the model can itself be assigned a length; and fourth, the optimal analysis of the data is the one for which the sum of the length of the compressed data and the length of the model is the smallest.