Do NJM7800 and NJM7900 series guarantee a dropout voltage in a data sheet?

LDO Linear Regulators

It is indirectly guaranteed in a line regulation test condition. A minimum input voltage is described in condition of Line Regulation item. A difference between minimum input voltage and output voltage is dropout voltage.
Therefore, the dropout voltage of NJM7805 is the minimum 2V at Io=0.5A, Tj=25 degree.