XL2000: Limitations for Naming Visual Basic Modules

In Microsoft Excel, the names of Microsoft Visual Basic for Applications modules are subject to certain limitations. This article explains these limitations and how to avoid problems when module names include illegal characters.

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Changing the Name of a Module in Microsoft Excel

In Microsoft Excel, you can rename a module by activating the module, clicking to the right of (Name) in the Properties window of the Visual Basic Editor, typing a new module name, and pressing ENTER.

You can also programmatically change the name of a module by using code similar to the following:

Limitations for Naming Modules in Microsoft Excel

In Microsoft Excel, module names can include the following characters:

• Alphanumerics (A-Z, a-z, 0-9)
  
  
• Underscore characters (_)
  
  

Illegal characters (characters that cannot be used in module names) include the following:

• Spaces ( )
  
  
• Exclamation points (!)
  
  
• Periods (.)
  
  
• Question marks (?)
  
  
• Commas (,)
  
  
• Any other nonalphanumeric characters

NOTE: Some characters that are illegal in Microsoft Excel are acceptable in earlier versions of Microsoft Excel.

Module names cannot exceed 31 characters in length.

Module names cannot start with a numeric character (0-9) or an underscore character (_). Module names must start with an alphabetical character (A-Z, a-z).

If you try to rename a module so that its name includes illegal characters, you will receive the following error message: where module name is the name of the active module sheet.

Names of Modules That You Created in Earlier Versions of Microsoft Excel

If you open a workbook that contains modules with names that include characters that are illegal in Microsoft Excel, the modules and the macros they contain are still available.

None of the modules are renamed by Microsoft Excel. However, if a module's name contains an exclamation point, the exclamation point is replaced on the screen by a question mark. However, the actual name of the module does not change.

For example, if you open a Microsoft Excel 5.0 or 7.0 workbook that contains the following three modules, Microsoft Excel may change the module names. The following table illustrates how the module names would appear.


Microsoft strongly recommends that you rename such modules so that their names do not include any illegal characters. For example, in the table above, rename the module from Module!1 to Module1 or Module_1.

Note that renaming modules may require that you modify your Visual Basic macro code wherever it refers to a module by name.

Exporting or Importing Modules with Names That Contain Illegal Characters

In Microsoft Excel, you can export a Visual Basic module to a separate file by activating the module and clicking Export File on the File menu. This works even if the module name includes illegal characters.

However, when you click Import File on the File menu and attempt to import a file, you may receive the following error message: where module name is the name of the module.

This problem occurs if the VB_Name attribute in the file contains any illegal characters.

To work around this problem, follow these steps:

1. On the Start menu, click Run. In the Open box, type Notepad, and click OK.
2. In Notepad, click Open on the File menu. Select the file you want to import into Microsoft Excel, and click Open.
   
   The first line of the file should look similar to the following example:
   Attribute VB_Name = "Module 1"
3. Change the name inside the quotation marks to a name that does not contain any illegal characters. For example, use Module1 or Module_1.
4. When you are done, click Save on the File menu. Then, click Exit on the File menu.

NOTE: If your Visual Basic module is very large, you may need to edit it using Wordpad or another text editor.