bóc-stæf
This might be just a supplemental entry adding to an entry in the Main Volume.
In the OE text, the length is:indicated by acute accentsindicated by macronsnot indicated.
bóc-stæf
Add: — Bócstæf hoc gramma, An. Ox. 18 b, 45. Ne cúþe hé nǽnige bócstafas (nequaquam litteras noverat), ac swáþeáh hé gebohte him sylfum þá béc þæs hálgan gewrites, and bæd man rǽdde þá béc beforan him. Gr. D. 281, 22. [v. N. E. D. hoc-staff. O. Sax. bók-staf : O. H. Ger. buoh-stab littera, character: Icel. bók-stafr.]
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A Combined List of Abbreviations.