How to do manual naming series in erpnext?


I need to create naming series which is to be enter manually at the time of save in doctype.


Perhaps you can try this
1.Go to ‘Setup’ Module → ‘Customize’ Menu → ‘Customize Form’ doctype
2. Select document for which you want to have Manual naming.
3. In ‘Fields’ datagrid , Click on ‘Series’ row.
Here in ‘Option’ textarea you can add new naming series for the form. You can set it as mandatory.

It can generate auto naming series but I want to enter series number manually.
How to manually enter the series number.