![](/assets/public_website/hand-blue-rtl-a46f7ad1402dcbcc8c8b101274d7fc11f962d84e8bc3d5dd0677d61a59eb148b.png)
Gaps (holes) in the numbering schemes
Although it should not normally occur, it may happen that a number of invoices remain unallocated.
If you have for example the * INV-XXXX * numbering scheme, from which the invoices * INV-0001 *, * INV-0002 *, * INV-0003 * but missing the invoice * INV-0184 *.
To be able to automatically detect all these gaps (holes) in the numbering scheme, there is a check function exemplified in the graph below.
![Gaps (holes) in the numbering schemes - step 1](/faqs/image/1058167488-gaps-holes-in-the-numbering%20schemes-1.png)
![](/assets/public_website/hand-blue-rtl-a46f7ad1402dcbcc8c8b101274d7fc11f962d84e8bc3d5dd0677d61a59eb148b.png)