Mission, vision and core values are part of the directional strategies of an organization. They set boundaries to the operations and assist an organization in doing its work.
Mission:
Represent what the organization is doing right now.
Vision:
Represent what the organization is trying to achieve in future.
Core Values:
Represent qualities of the operations or services. For example, "Respect Others" may be one of the core values of a company. It suggests that an employee should (actively) demonstrate respect to the co-workers and others external to the organization. Core values tend to glue the employees and others together.
Formulated and impregnated well into an organization, directional strategies become high power tools. For example, say an external company suggests a merger. Your mission and vision can easily decide whether you accept the offer or reject. A core value like "Excel in all services" encourages employees to do their best in every activity they perform. I guess you can now figure out why directional strategies are called directional strategies.