# Understanding Precedence

Precedence is a feature of the Expere Knowledge Base that allows custom content to supersede base content using a combination of inheritance and overrides. Precedence is applied by Precedence Units, which are discrete collections of content that are organized hierarchically. You may need to apply custom content to a specific Precedence Unit that will then be inherited by any child unit that does not override it.

Wolters Kluwer Financial Services is always the root (parent) Precedence Unit, at the top of the hierarchy and custom content resides in sub-levels below, as illustrated in the figure below. Any custom content in the Vestar Bank precedence unit will automatically apply to the Vestar Mortgage and Vestar Financial precedence units. Custom content in the Vestar Mortgage precedence unit will only apply to Vestar Mortgage and, likewise, custom content at Vestar Financial will only apply to Vestar Financial.

Parent topic: Custom Content and Precedence