Something an enterprise does, or needs to do, in order to achieve its objectives.
A Business Function delivers added value from a business point of view. It is delivered by bringing together people, processes and technology (resources), for a specific business purpose.
Business Functions answer in a generic sense "What business purpose does this Business Service or Process Step serve?" Through identifying the Business Function associated with each Business Service or Process Step it increases the documentation of the use of the associated Business Services and Process Steps, to enable future reuse.
A Business Function may be defined directly with descriptive text and/or through reference to an existing catalogue of Business Functions. The phases and sub processes defined within GSBPM can be used as an internationally agreed basis for cataloguing high level Business Functions. A catalogue might also include Business Functions defined at a lower level than "sub process". For example, "Identify and address outliers" might be catalogued as a lower level Business Function with the "Review, validate and edit" function (5.3) defined within GSBPM.