> > "íar" takes the dative
> I got the impression from the entry in the DIL that 'mad íar' is a
> shortened form of the expression 'mad íar do réir'.
This entry in DIL M 4.59 has to be read in a slightly different manner. I'll quote the beginning:
"similarly in the common formula: mad íar (do réir, etc.)
_(if it be) according to:..."
This means that in the formula "mad íar" OR "mad do réir" OR other formulas like it (e.g. "mad do"), the phrase means "according to". So it's not a question of an
abbreviated formula, but of two separate, but similar formulas.