Let's say that you have PTP_RS_004 on pages 5 and 27. Am I correct when I assume that you want PTP_RS_004 listed in an index followed by numbers 5 and 27?

In that case, you should enter PTP_RS_004 twice in the so-called concordance file (= any file that you save in Word format), which should contain a two-column table (and nothing else but that table) with PTP_RS_004 in the left cell of a row. Add a new row for each additional item you want to create in an index and add it as exemplified with PTP_RS_004. (Remember that the left column contains the items Word should search for when creating the index and the right column contains the corresponding index entries that you want to create.)

To create the index based on the concordance file, do the following: Open the document that should contain your index. Click References | Insert Index. In the dialog box, click AutoMark and locate the concordance file you created.

__________________
Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional