For system objects, the General tab of the object definition screen includes identification information, such as object name in the singular and plural forms, unique code, and an icon image file. Depending on the system object, some of these details may not be modified.
General Tab on Custom Object Definition Screens
See the General Tab on Custom Object Definition Screens table for details about the General tab of object definition screens. In addition to the General page fields in the table, the Expense, Invoice, and Task system objects include the following check-box:
Allow edits to custom fields after posting—Place a checkmark in this check-box for the Expense, Invoice, or Task object to allow users to edit custom fields after posting a record for that object.
See Customization Sequence for customizing a system object.