TCR in most cases refers to ambient temperature, however, if power is applied, resistive material itself gets hot. This heat also affects the resistive value resulting in an error in current sensing. This is why the Power Coefficient of Resistance (PCR) is important. The smaller the PCR, the less errors in current sensing. Large PCR means a large error near rated power. As this data shows, KRL series has ideal linearity as the amount of current increases.