We distinguished […] between A-positions in which A-GFs are defined [...] and Ᾱ-positions with Ᾱ-GFs [...] Ᾱ-GFs are adjuncts in constructions formed by Move-α; for example, the GF of the "wh"-phrase in COMP, or of an extraposed item, or of an NP adjoined to a VP by inversion in pro-drop languages.
- Chomsky (1993), a pag.178

The function chain (GF1, GF2) produced by a single application of "wh"-movement contains GF2, necessarily an A-GF, and GF1, a non-A-GF (Ᾱ-GF) that we may denote "adjunct to COMP".
- Chomsky (1993), a pag.47