Halliday & Matthiessen On Fawcett's Relational Processes

Halliday & Matthiessen (1999: 504): 

His abandonment of the distinction between attributive and identifying seems harder to motivate, since this cannot in fact be explained as a textual (thematic) system in the way that Fawcett proposes.

Halliday & Matthiessen (2004: 229):

Note therefore that Identified–Identifier cannot simply be explained as Given–New in an ‘identifying’ clause; not surprisingly, since the former are experiential functions whereas the latter are textual.