You can specify document numbering sequence and pattern.
Click menu "Document Settings", choose document type and choose "Document Number".
The "Document Number" dialog is shown.
Specify your numbering pattern.
0 - treat as the leading zero.
# - treat as the current document number
{YYYY} - 4-digits current year
{YY} - 2-digits current year
{M} - current month
Example 1
Numbering Pattern : REC#
Current Number : 2 => Output : REC2
Current Number : 23 => Output : REC23
Current Number : 345678 => Output : REC345678
Example 2
Numbering Pattern : REC0000#
Current Number : 2 => Output : REC00002
Current Number : 23 => Output : REC00023
Current Number : 345678 => Output : REC345678
Example 3
Numbering Pattern : REC{YYYY}0000#
Current Number : 2 => Output : REC202100002
Current Number : 23 => Output : REC202100023
Current Number : 345678 => Output : REC2021345678
You can also specify the starting number.
Click "Save" button when ready.
When creating a new document, document number is assigned automatically according to the settings.