A Block in AutoCAD is a reusable collection of objects (lines, arcs, text, circles, etc.) that are combined and stored under a unique block name. Naming a block correctly is important for organizing drawings, managing components, and ensuring consistency in engineering documentation.

This guide explains how to assign a block name, rename blocks, and apply best practices for block naming.

1. What is a Block Name?

A Block Name is the identifier used to store and call a block inside a drawing. It must be:

• Unique (no two blocks can share the same name)
• Descriptive
• Easy to identify

Examples of good block names:

• LIGHT_SWITCH_1G
• VALVE_TYPE_A
• DOOR_SINGLE_900MM
• TITLEBLOCK_A3

2. How to Create a Block and Set the Block Name

Step 1: Draw the objects

Draw the geometry you want to include in the block (e.g., symbol, component, furniture, etc.).

Step 2: Open the Block Definition window

Type the following command in the command line and press ENTER:

BLOCK

or simply:

B

The Block Definition dialog box will appear.

Step 3: Enter the Block Name

In the field Name, type your desired block name.

Naming rules:

• Cannot contain spaces — use underscore _ instead
• Cannot be empty
• Case-sensitive (recommended to use CAPITALS for clarity)
• Avoid special symbols such as * / ? : < > |

Example block name: SOCKET_OUTLET_13A

Step 4: Select the Base Point

Click Pick Point, then select a coordinate on your drawing that will act as the block insertion point.

Step 5: Select the Objects

Click Select Objects, then highlight all geometry to be included and press ENTER.

Make sure all required elements (lines, text, symbols) are selected.

Step 6: Confirm Block Settings

Choose one of the following options in the Block Definition dialog:

• Retain — Geometry stays as separate objects
• Convert to Block — Geometry becomes a block immediately
• Delete — Geometry is removed from the drawing after block creation (block only stored in the block definition)

In most cases, users choose Convert to Block.

Step 7: Click OK

Click OK to create the block. Your block is now stored with the chosen block name.

3. Verifying the Block Name

You can verify that the block has been created by using the INSERT command:

INSERT

A list of available block names will appear. Your newly created block should be listed.

4. Renaming an Existing Block

Method 1: Using the RENAME command

1. Type RENAME and press ENTER.
2. Select Blocks from the list.
3. Choose the block you want to rename.
4. Enter the new block name.
5. Click OK.

Method 2: Using Block Editor (BEDIT)

1. Type BEDIT and press ENTER.
2. Select the block to edit.
3. In the Block Editor, click Save Block As….
4. Assign a new block name.
5. Save and close the Block Editor.

5. Best Practices for Naming Blocks

To maintain clarity and consistency in CAD drawings, follow these naming standards:

1. Use uppercase letters

Easier to read and reduces naming confusion.

2. Use prefixes to categorize blocks

Examples:

• EL_ for electrical
• MECH_ for mechanical
• ARCH_ for architectural
• FD_ for furniture

Example: EL_SWITCH_1G

3. Include size or specification

Examples:

• DOOR_SINGLE_900MM
• VALVE_25MM_BUTTERFLY

4. Avoid unclear abbreviations

Poor example: BRKSW
Better example: BREAK_SWITCH_3P

5. Avoid using dates in names

Including dates in block names can make long-term drawings messy and difficult to reuse.

6. Managing Block Names in a Drawing

View all block names

Depending on the AutoCAD version, you can view blocks through the Insert dialog or block palette. One common way:

1. Type INSERT and press ENTER.
2. Use the drop-down list to view all available blocks in the current drawing.

Delete unused block names (Purge)

If your drawing contains outdated or unused block names, you can clean them up:

1. Type PURGE and press ENTER.
2. Select Blocks in the Purge dialog.
3. Click Purge All to remove unused blocks.

This helps reduce file size and keeps your drawing organized.

7. Troubleshooting Common Issues

Issue 1: “Block name already exists”

Cause: A block with the same name is already defined in the drawing.

Solution:

• Use a different block name, or
• Delete or purge the old block definition if it is no longer needed.

Issue 2: Block not appearing in the INSERT list

Possible causes:

• The block was not created correctly or was not saved.
• You selected the Delete option during block creation.
• The block definition was purged as unused.

Fix: Recreate or redefine the block and ensure it is saved properly.

Issue 3: Wrong base point causes misalignment

Solution:

• Use BEDIT to open the Block Editor and adjust the geometry relative to the base point, or
• Redefine the block using the BLOCK command with a correct base point.