When you are registering shooters for a match, each registration needs to have a unique shooter number.  If someone is registering in more than one division (CDP and SSP, for example), he needs a different shooter number for each division.  Or if he's reentered and shooting the same division twice in one match, he needs a separate shooter number for each registration.  (Jane is shooting SSP twice, using shooter numbers 15 and 55.  The yellow indicates a reentry - shooting the same division twice.  She is using shooter number 201 in the SIDE division.)

SIDE shooter numbers have some separate considerations and are discussed elsewhere.

When you are entering scores, you can select shooters by their name if you prefer.  Or by shooter number.

I find I'm somewhat less prone to error using shooter numbers - particularly in a large match where there may be multiple shooters with the same last names.  The optional Barcode module relies on shooter numbers for score entry, as does Direct Data Entry.

 

After you have created a match, you can have shooters renumbered by the Renumber Wizard if you have some need to do so.