1904 Errata appended. The ODNB strongly suggests that his existence was a fabrication.

594308Dictionary of National Biography, 1885-1900, Volume 01 — Aio1885Charles Francis Keary

AIO (d. 974), an historian, was a monk in the abbey of Croyland or Crowland in Lincolnshire, and is only mentioned in the ‘History’ of Ingulf, afterwards abbot of the same monastery. From this account we learn that after the death, in 941, of Athelstan, the special patron of Croyland, as well as of the abbot and two of the elder brothers, the monastery seemed likely to fall into decay. There remained in it only five monks, and of these two, Brun and Aio, in despair of the future of Croyland, determined to retire to other religious houses. Brun went to Winchester and Aio to Malmesbury. Croyland was, however, restored to prosperity in 946 by Eadred, who appointed Turketul abbot, and in the same year Brun and Aio were recalled thither. To these two monks was entrusted the task of compiling a history of Croyland, but they did not live to complete their task, both dying in the same year, 974. Ingulf professed to have made use of material collected by them.

[Historia Ingulphi, in Rer. Anglic. Script., ed. Gale, pp. 29 seq., 51.]

Dictionary of National Biography, Errata (1904), p.4
N.B.— f.e. stands for from end and l.l. for last line

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199 i 28 Aio (d. 974): Note The only authority for the existence of Aio is the spurious 'history' of Ingulf, abbot of Croyland