The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, , at sacred-texts.com
There are two calculations of years: one is the year of the sun, consisting of 365 days; the other is the year of the moon, having 354 days. The days which are over and above the number of the lunar year are called days of days, and they are thus distributed among the Albans, that is to say;--two days of days to Alban Arthan, three to Alban Eilir, three to Alban Hevin, and three to Alban Elved. They are free days, and let any one come from any place he may, he will be free, and exposed to no weapon or stroke, since there can be no court and law of country on those days. 1
(Bardism; fragments of the Months and other things.)
425:1 p. 424 "Days of days are those on which it is not proper to prosecute a suit." Welsh Laws.
Dr. Pughe renders "dyddiau dyddon," by blank days;--
The life of Davydd is like a blank day.--D. Benvras.