Warton gives the reference, viz. to his Speculum Historiale, lib. vii. c. 90, fol. 86 a.
I.e. it is the sole authority for placing both the Shipman's Prologue and his Tale precisely here. At the same time, at least seventeen other MSS. make the Shipman's Prologue follow the Man of Law's Tale; only they turn it into a Prologue for the Sompnour or Squire.
The Monk's cell is mentioned in the Prologue, l. 172; Chaucer's was his 'celle fantastyk'; Kn. Ta. 518 (A 1376).
I put (e) not (b), in order to show the chronological order, which is that of the letters, a, b, c, d, e, f.
The group (f) has nothing to do with (e); as will appear.