For more information about ICD-9-CM, please click here
http://www.cdc.gov/nchs/about/otheract/icd9/abticd9.htm

For more information about e-codes, please click here
http://www.allina.com/ahs/foundation.nsf/page/AF_vp_ecodes

For information about Reason for Visit Classification used with the NAMCS and NHAMCS, please click
http://www.cdc.gov/nchs/data/rvc97.pdf