  This paper studies new bounds and constructions that are applicable to the
combinatorial granular channel model previously introduced by Sharov and Roth.
We derive new bounds on the maximum cardinality of a grain-error-correcting
code and propose constructions of codes that correct grain-errors. We
demonstrate that a permutation of the classical group codes (e.g.,
Constantin-Rao codes) can correct a single grain-error. In many cases of
interest, our results improve upon the currently best known bounds and
constructions. Some of the approaches adopted in the context of grain-errors
may have application to other channel models.
