# Understanding Field Inheritance

Field inheritance is a powerful way to manage shared and type-specific fields with a minimum of duplication and administrative overhead. Some fields, like _Name_, _Title_, and _Document Number_, are universal and apply to all documents. Other fields only make sense for particular document types. For example, _MLR Approval Type_ only applies to a _Promotional Piece_ document that goes through a Medical Legal Regulatory review.

The general concept of field inheritance is to use the document type tree structure as a way of specifying the scope of where a document field applies. "Field inheritance" is the implied cascading application of the field from nodes of the tree structure to its children nodes:

  * Fields defined at the _Base Document_ level apply to all documents.
  * Fields defined at the _Type_ level apply to documents of that specific document type and all of its subtypes and classifications.
  * Fields defined at the _Subtype_ level apply to documents of that subtype and all of its classifications.
  * Fields defined at the _Classification_ level apply to documents of that specific classification only.

The fields of a particular document are a composite of the fields defined for Base Document, Type, Subtype, and Classification.