Based on the 2-3 lower-voice suspension in species counterpoint, this third inversion chord typically resolves to a first inversion chord. In Ex. 8.6, the intervallic "2" is formed by the outer voices whereby the bass A then resolves downwards to G#. In Ex. 8.6g & 8.6h, this 2-3 suspension element is found between the tenor and bass parts. Ex. 8.7 provides a musical example from Haydn.
V4/2-I6 is perhaps one of the most common instance of this bass suspension progression but the latter can be applied to other progressions too. Nor does the dissonant "2" need to be prepared in the manner of a suspension--it can be introduced in the form of a passing note.
Ex. 9.4a - note the P4/2 (IV4/2) between IV and viio6.