Hello,
I want the numbering to be something like REQ_0001, REQ_0002, REQ_0003 and so on. How to create this type of numbering having 4 digit numbers with leading zeros? I could create numbering format with only two digits such as REQ_01.

In the absence of any information about what you may be numbering, I can only point out the possibility of using a formatting switch. e.g. You could use SEQ fields to create the numbering.

{ SEQ MyNumber \# "'REQ_'0000" }

(The brackets { } are inserted with CTRL+F9 Save as Autotext or autocorrect for ease of re-insertion).

The only downside is that the SEQ fields do not update automatically. You can use F9, or you may find it more convenient to add a macro to the QAT (Quick Access Toolbar) to facilitate updating. The example, code at http://www.gmayor.com/installing_macro.htm will do the job.

__________________
Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com

If this is paragraph numbering, you can choose the "0001, 0002, ..." format in the Multilevel List dialog box. At least that format is offered in Word 2013 (I can't test Word 2010 right now). Click Home tab | Multilevel List | Define New Multilevel List.

The best approach to multilevel lists is setting them up with styles; see http://shaunakelly.com/word/numberin...g20072010.html.

__________________
Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional