Optical Power: 20dB (This likely refers to a signal strength or attenuation, but without further context, it's ambiguous. It could also refer to a nominal output power level. Given the context of a 'Tx' card and '20dB', it's most likely indicating a nominal output power level or a specified signal-to-noise ratio, but '20dB' alone is a broad specification. Assuming it represents a performance metric or output characteristic.)