2004

Create and Insert Symbols (Blocks) | 317
When you insert a block, you are inserting a block reference, AutoCAD does
not simply copy the information from the block definition to the drawing
area. Instead, a link is established between the block reference and the block
definition. Therefore, if the block definition is changed, all references are
updated automatically.
To reduce the size of a drawing, you can purge unused block definitions.
Create Blocks
You create blocks by associating objects and giving them a name. You can
also attach information (attributes) to a block.
Create Blocks Within a Drawing
After you define a block in a drawing, you can insert a block reference in the
drawing as many times as necessary. Use this method to create blocks
quickly.
Each block definition includes a block name, one or more objects, the coor-
dinate values of the base point to be used for inserting the block, and any
associated attribute data.
The base point is used as a reference for positioning the block when you
insert it. Suppose you specify that the base point is at the lower-left corner of
an object in the block. Later, when you insert the block, you are prompted
for an insertion point. AutoCAD then aligns the block base point at the
insertion point you specified.
The block definition in the illustration comprises a name,
PLUG_VALVE, four
lines, and a base point at the intersection of the two diagonal lines. For an
explanation of the schematic representation shown, see “Overview of
Blocks” on page 316.
empty drawing
file with block
table
block definition
stored in block
table
block references
inserted in drawing
area