1. INTRODUCTION

2. OBSERVATIONS AND SAMPLE CHARACTERISTICS  
2.1. The CRIRES Survey  
2.2. Sample Selection  
2.3. Observing Procedure and Data Reduction  
2.4. Detection Rates  
2.5. Multiplicity  
2.6. Extended Emission  
2.7. Temporal Variability  

3. CLASSIFICATION OF CO LINE PROFILES  
3.1. Emission Profiles  
3.2. Absorption Profiles  
3.3. Absence of CO Lines  

4. CO EXCITATION  
4.1. Rotational Temperatures  
4.2. Vibrational Excitation  

5. DISCUSSION  
5.1. Where is the CO Gas Located?    
5.2. Temperature Structure of the Inner Disk Region  
5.3. Effects of Stellar Mass on CO  
5.4. Evolutionary Changes in CO  

6. CONCLUSIONS