...a well informed member of your company who has mastered a subject in its entirety.

A subject matter expert is a person in your organization that has 100% understanding about a certain product or service that your company provides. This person usually has a low level grasp on how this service or product integrates and effects other products or services your company provides. Subject matter experts are usually assigned the task of Editor for their partition.

This person is then in charge of publishing content and making sure that the content is within the guidelines of company procedures.