The General Manuscript Collection of the National Library of Wales includes three series of manuscripts: NLW Manuscript series; NLW ex series of Manuscripts; and, NLW Rolls. All manuscripts acquired by the library through either donation or purchase are added to this open-ended series, either singly or in groups, if they are: a) in a format compatible with the collection, i.e. manuscript books or rolls, or unbound material that can be filed; and, b) not integral to an archive or individual collection. There is, however, much archival material, mostly correspondence, held in the General Manuscripts Collection. The holdings in the General Manuscript Collection are catalogued in the Handlist of manuscripts in the National Library of Wales, which focuses on those manuscripts in the National Library which are not part of the foundation collections; there were over fifteen thousand when the first volume of the handlist appeared in 1940, and the collection had increased to 23,233 by 31 March 1994.