Hello All,

I got the solution of my above question.

The solution is:

To generate custom invoice number, you have to make changes in "ir_sequence.py" file. This file is located on following path - C:\Program Files\OpenERP 7.0-20130917-231058\Server\server\openerp\addons\base\ir

Note: Above path may vary in different environment.

Now Open that file and find this method - _interpolation_dict(self): do changes in this method as per your requirement. (Though it is not advisable to make changes in this type of file because when you update openerp then this type of changes might be lost.)
This function return dictionary, and then whatever result is there, you can use it in invoice sequence.

e.g. In openerp sequences we can insert current financial year - SAJ/%(cur_fin_year)s/ instead of SAJ/%(year)s/... where cur_fin_year is my custom defined key in above method.

That's it.

Regards,

Krishnraj