This layer holds the adcadd_zz block which, in turn, holds
some drawing setup data (horiz / vert scale, etc.) and the
link to your project. Rather that use any layer (including
0), Softdesk opts to create a layer that >probably will not<
(read >should not<) be used for normal work product.
--
Karl M. Fuls PLS
Member of the Autodesk Discussion Forum Moderator Program