Responsibility Assignment Matrix:

Responsibility assignment matrix (RAM) is typically used to link activities to resources to ensure that the scope's components are each assigned to an individual or team. One type of RAM is based on the RACI format (Responsible, Accountable, Consult and Inform). This type of RAM is called a RACI chart, because it assigns the role that the resource is to play for each given activity. These charts can be constructed at a high level (general areas) or at a detailed level (low level tasks). A table is drawn, usually with Activities on the vertical edge (Work Breakdown Structure or WBS) and Resources on the horizontal edge (Organization Breakdown Structure). Not every resource will have an entry for every activity. As an illustration, please consider this simple chart:

ACTIVITIES	George	Glenda	Tom	Susan	Mary	Craig
Investigate	R	A	I	C	C	-
Design SW	I	A	C	-	-	R
UAT Plan	R	A	I	-	-	C
Phase Signoff	R	A	I	C	C	C

Two other RAM versions are the RACI-VS format, adding the additional roles of Verifies and Signs, and the RASCI version, adding the additional Supportive role. The definition of each role is listed below:
Role Definition
Responsible This role conducts the actual work/owns the problem. There can be multiple Rs (this is called team working)
Accountable This role approves the completed work and is held fully accountable for it. There should be only one A
Supportive This role provides additional resources to conduct the work or plays a supportive role in implementation.
Consulted This role has the information and/or capability to complete the work. Two-way communication (typically between R and C).
Informed This role is to be informed of progress and results. One-way communication (typically from R to A).
Verifies This role checks the work to ensure that it meets all defined criteria and standards.
Signs This role signs off on the completed work.
A responsibility matrix can also be known as a linear responsibility chart and can be used to show who is responsible and at what level. For example each row could represent a task and each column a person, the boxes could then be completed with the letters P (Prime support), S (Support) and N (Notify).
LRC is often referred as the responsibility assignment matrix (RAM). It identifies the participants, and to which degree each activity will be performed and/or decisions will be made.