This PmTcaThresholdType value defines how to interpret the number stored in the sibling cienaCesPmAdjustmentTcaLastIntvlEndTcaThresholdValue object, per its DESCRIPTION -- for instance, whether that recorded value should be read as an absolute count or as a percentage. Without this type indicator, the frozen threshold value recorded for a historical TCA would be ambiguous in exactly the same way a raw AdjustmentThreshold number is ambiguous without knowing whether the live profile used the fixed or the percentage-based threshold object; this snapshot preserves which one was actually in force for that specific past event. For example, this reading 'percentage' tells you the accompanying ThresholdValue of 15 should be read as '15 percent of the basis', not as a raw count of 15 units.