Neil McLeod wrote:

>> BB Neartais a aes luaig nan diaid
>> Lec Neartais aes sluaig na ndiaidig

> In line (a) of BB 
> 'nandiaid' should be divided 'na ndiaid' (as in Lec). And since we need 
> - a final disyllable; and
> - 8 syllables in the line; and
> - consonance with disyallbaic 'di-ib',
> we can be pretty confident that we should follow Lec in reading 
> 'ndiaid[ig]'.

Alas, being 'pretty confident' is not the same as 'being correct'.

DIL D 171.20: "In early Mid. Ir. poetry" the word 'diaid' was 
"occasionally disyllabic to meet the requirements of the metre". So 
Lec's spelling may be just an orthographic represention of the 
disyllable = /dia(dh)-idh/, and BB's spelling is preferable.

Furthermore, the first 'i' is long: 'díaid', as is shown by the rhyme 
with 'rîad' in SR 595 - see DIL D 171.43-44.

That means that the consonating words at the ends of each of the other 
lines also start with a long vowel.

So, let me try again:

BB fol 108 r col a

Neartais a aes [s]lûa(i)g na ndîaïd
nirbo trûag in tôoïr
co Sliab Cuillind îar crîch dîïb
for-uirim crîch dôïb

Lec fol 221 v col a

Neartais [a] aes slûa(i)g na ndiai(d)ig
nirbo trú(?)ag in tôaïr
co Sliab Cuillind îar crîch dîïb
for-fuirim crîch dôïb

Neil