Strictly speaking the Ruthenian Recension refers to the liturgical books produced at Rome from from 1940-1973 at the request of the Greek Catholic bishops of what are now the Ukrainian, Rusyn, Slovak, Hungarian, and Croatian Greek Catholic Churches. Long story short, all available manuscripts were consulted both pre-Nikonian and Nikonian. When pre-Nikonian texts agreed they were followed, when they didn't, Nikonian use prevailed, so in some instances Ruthenian practice agrees with the Old Rite, in others the Nikonian. The request was made in order to purify the usage of Latinizations which had been adopted after the unions. In general, where Ruthenian Use differs from Nikonian the Ruthenian use is more ancient. It should also be noted the Old Rite itself accepted some reforms prior to Patriarch Nikon's, so it does not always reflect the more ancient usage itself.