2013

This could happen, for example, if you have a BL:NAME field with a width of
8 characters and a block in your drawing has a name 10 characters long.
Modify Blocks
You can modify a block definition or a block reference already inserted in the
drawing.
Modify a Block Definition
When you redefine block definitions in your current drawing, both previous
and future insertions of the block in the drawing are affected.
You can redefine block definitions in your current drawing. Redefining a block
definition affects both previous and future insertions of the block in the current
drawing and any associated attributes.
There are two methods for redefining a block definition:
 Modify the block definition in the current drawing.
 Modify the block definition in the source drawing and reinsert it into the
current drawing.
The method you choose depends on whether you want to make changes in
the current drawing only or in a source drawing also.
Modify a Block Definition in the Current Drawing
To modify a block definition, follow the procedure to create a new block
definition, but enter the name of the existing block definition. This replaces
the existing block definition, and all the references to that block in the drawing
are immediately updated to reflect the new definition.
To save time, you can insert and explode an instance of the original block
and then use the resulting objects in creating the new block definition.
Update a Block Definition That Originated from a Drawing File
Block definitions created in your current drawing by inserting a drawing file
are not updated automatically when the original drawing is modified. You
can use INSERT to update a block definition from the drawing file.
Create and Modify Blocks | 333