1948, Language: Journal of the Linguistic Society of America,page 46:
Seip has [... pointed] out that the e caudata (ę) was common in both Latin and English manuscripts of the period. An o caudata could easily have been formed by analogy with this character.
2004, O E Haugen, Parallel views: Multi-level encoding of medieval Nordic primary sources, in Literary and linguistic computing:
[…] amount of paleographical detail, such as the comparative height and width of the characters, hair lines, and minute allographic variation in letter forms, etc […] on this level is identical with that of Modern Icelandic, with the addition of the character 'o ogonek' (or ‘o caudata’), […]