What doc. they are? How can i find it for myself?

Hey, im editing print format, and i need to get this values: phone customer, payment condition, validity of the proposal, stock and including taxes.
Thanks, and please, appoint me where can i get the name of doc

Check the field names in customize form -> Name of doctype (eg. Sales Invoce)

Its this?

refer: https://frappe.github.io/erpnext/user/manual/en/customize-erpnext/customize-form

My form is already customized, i just wanna get some values like this:

You can get the field name from Customize Form:

and access it in custom print formats like this:

doc.field_name

For example:

doc.payment_condition