Hi,
You can set default values using the DocField’s “Default” field. What do you mean by “Mark” field?
Default records can be uploaded during app installation using “fixtures” system.
You have to specify a value in hooks.py as fixtures = ["Some DocType"]
https://github.com/frappe/erpnext_org/blob/master/erpnext_org/hooks.py
Then running: frappe sitename --export_fixtures will export all records of that doctype in app_name/fixtures folder
https://github.com/frappe/erpnext_org/tree/master/erpnext_org/fixtures
Then, when installing an app, these fixtures get imported automatically in the database.
Thanks,
Anand.