Editing Block Definition (Block Redefinition)
Block definitions stored in a document can be modified. Change of a block definition (block redefinition) can influence not only on block references newly created in the current drawing, but also on already created, as well as on any attributes associated with this block.
Since there are two ways to insert blocks in the current drawing (both stored in a document, and from the external file), there are also two ways to redefine blocks:
· Block redefinition in the current document.
· External file change and its redefinition in the current document.
Block redefinition in the current drawing
In most cases blocks are redefined in the Block Editor opened by the BEDIT command.
In addition, a block can be redefined manually by re-creating the block with the same name. To redefine the block manually, you should:
1. Insert the block in the drawing with its breaking into component objects by selecting the Explode checkbox in the Insert block dialog box or split the block reference available in the drawing by the Explode command from the Edit menu.
2. Edit the component objects.
3. Perform all actions to create a new block, but enter the name of the block being redefined.
Immediately after the block redefinition all references of this block available in the drawing are updated automatically.
Block redefinition from the external file
Block redefinition from the external file is performed similarly, if there is no necessity to change the external file.
Change of the external file has no influence on the current drawing, in which it is inserted as a block. To redefine (update) this block in the current drawing, it is necessary to insert it again.
Redefinition of block attributes
When redefining blocks, it is possible to change the definitions of attributes included in them.
Change of attribute definitions while redefining blocks influences on block references already created in the current drawing as follows:
· New variable attributes do not appear in existing block references.
· Old variable attributes remain in the existing block references, even if the redefined block does not have attributes at all.
· New constant attributes in the existing block references are added to the old ones.
· Old constant attributes (having fixed values) will be lost, if the redefined block has no attributes at all, or replaced by new values specified for the redefined block.