----------------------------Original message---------------------------- It may be presumptuous from a non-librarian, but wouldn't a good rule of thumb be to determine how a multi-sheet map is updated? The USGS 7.5' maps, for example, are updated (or not) individually, but the DMA six-map set is updated as a unit. Libraries, retailers, users, and even the DMA may break the six-sheeter up, but if the production process treats a multi-sheet map as a unit, shouldn't it be catalogued as a unit? -- Nat Case HEDBERG MAPS, INC ----------------------------------------------- Publishers of Professor Pathfinder Maps ----------------------------------------------- Production Office: [log in to unmask] Business office: [log in to unmask]