  Asymptotic symmetries of black hole spacetimes have received much attention
as a possible origin of the Bekenstein-Hawking entropy in black hole
thermodynamics. In general, it takes hard efforts to find appropriate
asymptotic conditions on a metric and a Lie algebra generating the
transformation of symmetries with which the corresponding charges are
integrable. We here propose an alternative approach to construct building
blocks of asymptotic symmetries of a given spacetime metric. Our algorithmic
approach may make it easier to explore asymptotic symmetries in any spacetime
than in conventional approaches. As an explicit application, we analyze the
asymptotic symmetries on Rindler horizon. We find a new class of symmetries
related with dilatation transformations in time and in the direction
perpendicular to the horizon, which we term superdilatations.
