What is continuous and staged representation?

CMMI contains 25 key process areas which organization can follow to adapt CMMI.

Causal Analysis and Resolution (CAR)
Configuration Management (CM)
Decision Analysis and Resolution (DAR)
Integrated Project Management (IPM)
Integrated Supplier Management (ISM)
Integrated Teaming (IT)
Measurement and Analysis (MA)
Organizational Environment for Integration (OEI)
Organizational Innovation and Deployment (OID)
Organizational Process Definition (OPD)
Organizational Process Focus (OPF)
Organizational Process Performance (OPP)
Organizational Training (OT)
Product Integration (PI)
Project Monitoring and Control (PMC)
Project Planning (PP)
Process and Product Quality Assurance (PPQA)
Quantitative Project Management (QPM)
Requirements Development (RD)
Requirements Management (REQM)
Risk Management (RSKM)
Supplier Agreement Management (SAM)
Technical Solution (TS)
Validation (VAL)
Verification (VER)
The method by which company wants to adapt to CMMI is called a representation. So either organization can adapt for staged or continuous representation. In the continuous representation process areas are organized by functional area. For example, a company interested to improve its Project Management capability would focus on IPM, ISM, IT, PMC, PP, QPM, RSKM and SAM.
Process Management
OID - Organizational Innovation and Deployment
OPD - Organizational Process Definition
OPF - Organizational Process Focus
OPP - Organizational Process Performance
OT - Organizational Training
Project Management
IPM - Integrated Project Management
ISM - Integrated Supplier Management
IT - Integrated Teaming
PMC - Project Monitoring and Control
PP - Project Planning
QPM - Quantitative Project Management
RSKM - Risk Management
SAM - Supplier Management Agreement
Engineering
PI - Product Integration
REQM - Requirements Management
RD - Requirements Development
TS - Technical Solution
VAL - Validation
VER - Verification
Support
CAR - Casual Analysis and Resolution
CM - Configuration Management
DAR - Decision Analysis and Resolution
MA - Measurement and Analysis
OEI - Organizational Environment for Integration
PPQA - Process and Product Quality Assurance
Staged representation
While in staged representation the concept of levels comes in to picture. In the staged representation process areas are organized by organizational maturity level. For example, a company interested to obtain a Maturity Level 2 rating would require company processes covering all of the Maturity Level 2 process areas.
Maturity Levels 2
CM - Configuration Management
MA - Measurement and Analysis
PMC - Project Monitoring and Control
PP - Project Planning
PPQA - Process and Product Quality Assurance
REQM - Requirements Management
SAM - Supplier Management Agreement
Maturity Level 3
DAR - Decision Analysis and Resolution
IPM - Integrated Project Management
ISM - Integrated Supplier Management
IT - Integrated Teaming
OEI - Organizational Environment for Integration
OPD - Organizational Process Definition
OPF - Organizational Process Focus
OT - Organizational Training
PI - Product Integration
RD - Requirements Development
RSKM - Risk Management
TS - Technical Solution
VAL - Validation
VER - Verification

Maturity Level 4
QPM - Quantitative Project Management
OPP - Organizational Process Performance
Maturity Level 5
CAR - Casual Analysis and Resolution
OID - Organizational Innovation and Deployment