About measure in carbon

[Sea]

Hi, all:
    I find the following codes in carbon CarbonCommonConstans.java. What does 
these measures mean??    Can I add a type for SHORT_VALUE_MEASURE = 's' ?





/**
 * DOUBLE_VALUE_MEASURE
 */
public static final char SUM_COUNT_VALUE_MEASURE = 'n';
/**
 * BYTE_VALUE_MEASURE
 */
public static final char BYTE_VALUE_MEASURE = 'c';
/**
 * BIG_DECIMAL_MEASURE
 */
public static final char BIG_DECIMAL_MEASURE = 'b';

/**
 * BIG_INT_MEASURE
 */
public static final char BIG_INT_MEASURE = 'l';