Description:
Inheritance is used to add or replace a field into a particular view in odoo. Inheritance specs are comprised of an element locator, to match the inherited element in the parent view, and the children element that will be used to modify the inherited element.
There are three types of element locators for matching a target element:
An XPath element with an expr attribute. expr is an XPath expression applied to the current arch, the first node it finds is the match.
A field element with a name attribute, matches the first field with the same name. All other attributes are ignored during matching.
Any other element: the first element with the same name and identical attributes (ignoring position and version attributes) is matched.