AutoCAD drawing database (DWG) can contain various types of anonymous (unnamed) blocks. The pseudo-names of anonymous blocks always start with an asterisk "*". You normally cannot use AutoCAD block editing commands with anonymous blocks. Examples of anonymous blocks:
*U### - general anonymous blocks *E### - anonymous blocks from non-uniformly scaled blocks - when exploded (e.g. solids, regions) *D### - anonymous dimensions (dim blocks) *X### - anonymous hatches (hatch blocks) *A### - anonymous groups *T### - anonymous blocks in tables AutoCAD add-on applications may create also other types of anonymous blocks.