 Y′ values are conventionally shifted and scaled to the range [16, 235] (referred to as studio swing or "TV levels") rather than using the full range of [0, 255] (referred to as full swing or "PC levels").This practice was standardized in SMPTE-125M in order to accommodate signal overshoots ("ringing") due to filtering.The value 235 accommodates a maximal black-to-white overshoot of 255 − 235 = 20, or 20 / (235 − 16) = 9.1%, which is slightly larger than the theoretical maximal overshoot (Gibbs phenomenon) of about 8.9% of the maximal step.