Niall Gallagher wrote - 
>There are three different spellings for the same (?) word, "báegul"' error:  baoghal , baedhal and baegal. Is the difference significant or just misspelling? 

Hi Niall,
   My impression is that spelling was not standardized in those days, and that variations were acceptable, as long as they were readable and as long as the different spellings had the same pronunciation.
    
The variation 'dh' and 'gh' is fairly common and I think the pronunciation was the same. 
The variation 'g' means that the scribe neglected to indicate lenition of the 'g', which is not crucial  because anyone who read the text would automatically know to pronounce the word with lenited 'g'.
Lack of the fada on 'ae' is not unusual either, as fadas are often missing from words in manuscripts.  Again, the reader would know how to pronounce the word without them. 
I am not completely certain about 'ao' versus 'ae', but I suspect they were often interchangeable and sounded the same much of the time.  
I  notice variants where 'a' and 'u' are interchanged.  I suspect they were pronounced the same in unstressed syllables at some stages of the language.   In 'baoghal',  the second syllable probably had a schwa sound. 

I am not an expert in this area, but I came to these conclusions by looking at texts, and by analogy with Modern Irish. 

Modern Irish has had a lot of spelling variation, especially before the spelling was standardized in the 20th century.   But the variants were readable and pronounced the same.  Liz
  


>> l Ni tualuing bretemnacht la Fene for otrus nat fiastar tri baegla otrusa.1
>> 
>> gloss -- 
>> 1 .i. tri hernaili ima mbaodhlaighther inti doni in otrus .i. baoghal can a
>> dingbail fo cetoir munob cunntabartac bais, 7 baedhal a dingbhail riasa .ix. masa cunntabartac bais, 7 baegal cen a dingbail iarsin .ix., cidh cunntabartac
>> bais cin cob ed, acht munar focaill sai legha comad marb e. no baegal cen biadh 7 can liaigh 7 can fir mama modh