AutoCAD Tips
How to Modify Block Definition in AutoCAD (How to Edit Blocks)
Modify an AutoCAD block definition by exploding and redefining, using the Block Editor, editing in place or inserting a newer version of the block.
AutoCAD Tips
Convert Anonymous Blocks *U### to Normal AutoCAD Blocks
What AutoCAD anonymous blocks (*U###) are, why they cause trouble, and how a free LISP converts them into normal, editable blocks.
AutoCAD Tips