CH_* - Metric that illustrates how value of metric * for a package was changed over the time. Positive number shows increase in value, negative - decrease.
CH_CLOC - Change in Number of Lines that contain comments.
CH_NCSS - Change in Number of non Commenting Source Statements. NCSS counts the number of source statements excluding blank lines, and comments. The value is not affected by the code style.
CH_NOM - Change in Number of Methods in the package.
CH_WMC - Change in Weighted Method Count. WMC is the sum of the McCabe's Cyclomatic Complexity values of all methods in the package.
