Hi there.
I did some research on this topic and the solution is wery simple.
When you create an ID-field, or an autonumber field, simply put in "Your code" 0000 at Format in your table properties at that field in your table.

Example: If you want to create a unik WorkOrder counting:

In table properties:
Format: "WO " 0000

Creates WorkOrder ID-number as follow:

WO 0001
WO 0002
WO 0003
... and so on...

Or a customer ID: (CU=customer)
Format: "CU " 0000

Creates:
CU 0001
CU 0002
CU 0003
... and so on.

This makes you able to name all your ID-number so that you know when you read a number you do know exact what kind of number this is.

If a customer calls you and gives his/her CU 0005 you know all about that customer. And the same about a WorkOrder, purchase order ad so on...

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Reply from Alex Hedley:

Thanks for the Tip Ronny.