We've already looked at the two notes in LB in which the scribe  
addresses Domnall:

"Ata in spideog derg uli, a Domnaill, ocus atusa am oenur."

=  The robin is all red, Domnall, and I am all alone.

"Dorignes in timroscc cétnai, a Domnaill."

=  I made the same mistake, Domnall.

I think it's likely that the marginalia which I just posted concerning  
the robin and the cat are also addressed to Domnall  ("ar catt" = "our  
cat") as well.

Murchadh Ó Cuindlis also copied out a portion of the Yellow Book of  
Lecan (cols. 281-344).  He left the following down-beat note there a  
number of years before doing LB:

"ata in dub ag leagad 7 ata Domnall sa galar farír"