Encoding vs Decoding Clauses In Logogenesis

Halliday & Matthiessen (2014: 283-4):

Identifying clauses of different coding orientations make distinct and complementary contributions in the development of text. Thus ‘encoding’ clauses serve as a resource for presenting the steps in the organisation of a text …  In contrast, ‘decoding’ clauses can be used as a strategy for interpreting phenomena that have been observed …