Found:
demotion
MORPHOLOGY/SYNTAX: the phenomenon that a subject (or external argument) becomes an optional oblique phrase or adjunct due to some morphological or syntactic operation. EXAMPLE: if we form the passive of break (= broken), the subject (or external argument) is demoted to become an adjunct (= the by-phrase):
(i) Tom broke the vase (ii) The vase was broken (by Tom)
LIT. | Marantz, A. (1984) Spencer, A. (1991) Williams, E. (1981b) |