This .pdf has an excellent description of HCC Models, V12, V22, V23 Chronic Condition Data Warehouse – CCW User Guide: Medicare Risk Score Files July 2018 Version 1.0 P 8, Version 12 (V12) was available through 2014. P 9, Version V21, V22 https://www.ccwdata.org/ documents/10280/19002246/ccw- medicare-risk-score-user- guide.pdf It can also be found off the home page, look for Analytic Guidance tab > then CCW Medicare Risk Score Files User Guide I am not affiliated with them in any way. Just sharing a good explanation I came across.