A balanced incomplete Block Design is called resolvable if there exists a Partition of its set of blocks into Parallel Classes, each of which in turn partitions the set . The partition is called a Resolution.
See also Block Design, Parallel Class
References
Abel, R. J. R. and Furino, S. C. ``Resolvable and Near Resolvable Designs.''
§I.6 in The CRC Handbook of Combinatorial Designs
(Ed. C. J. Colbourn and J. H. Dinitz). Boca Raton, FL: CRC Press, pp. 4 and 87-94, 1996.