Issue:

When opening a drawing and checking block names, some contain prefixes such as *U12 or *A5.

What are anonymous blocks, why do they appear, and do they affect the drawing?

Causes:

Anonymous blocks are system-generated blocks that users cannot create or rename manually.
Their names typically start with *U or *A (e.g., *U12, *A3).
They are a core mechanism in ZWCAD that allows independent modification of block instances without changing the original block definition.

Solution:

The following operation might generate an anonymous block

  1. Flexblock copy and modify (most common, most likely).
    Copying a Flexblock and changing its visibility, parameters, or flipping it automatically converts the copy into an anonymous block.
    The name shown in the Properties panel remains unchanged, but the anonymous name appears when using the LIST command.

    This is a normal and healthy operation, indicating that the link between the copied block and the original block is maintained.

  2. Using the Array command
    When using the ARRAY command in earlier versions, such as ZWCAD 2016, associative array objects are encapsulated into anonymous blocks.
  3. XREF Binding
    When binding an XREF to the current drawing, ZWCAD may convert some blocks into anonymous blocks.
  4. API
    Anonymous blocks can also be created manually using LISP, VBA, or ObjectARX tools.

Note:
When a block name in the Properties panel has a *U or *A prefix, the link to the original block is broken,
the anonymous block cannot be modified directly and must be exploded before editing.


CN Solution
JP Solution


★What is anonymous block in ZWCAD?：https://confluence.zwcad.com/pages/viewpage.action?pageId=323749706

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