Martin & Rose (2007: 310) place 'reading' on the cline of instantiation as more instantial than the text:
However, this is untenable for two reasons. Firstly, a reading of a text is at the same level of instantiation as the text it is a reading of. Secondly, a text is an instance of the system of the speaker/writer, whereas a reading is an interpretation of a text by a listener/reader.
As Halliday & Matthiessen (1999: 384) explain:
If we look at logogenesis from the point of view of the system (rather than from the point of view of each instance), we can see that logogenesis builds up a version of the system that is particular to the text being generated: the speaker/writer uses this changing system as a resource in creating the text; and the listener/reader has to reconstruct something like that system in the process of interpreting the text — with the changing system as a resource for the process of interpretation. We can call this an instantial system.
On this basis, a reading is variant instantial system that is reconstructed by a listener/reader of the instantial system of a speaker/writer.
