Consider not one PMO but several PMOs
The PMO (project management office)

The PMBok ( project management body of knowledge ), a PMI reference – Project Management Institut – defines the role of the project management office as follows.

"A project office is an organizational entity or unit charged with various centralized and coordinated management-related responsibilities for projects within its domain. The responsibilities of a project office can range from the provision of project management support functions to direct responsibility for a project".

In the remainder of this document, the acronym PMO will first be used to refer to the project management office, and then to project management officers.