  The origin of soft X-ray excess emission from type 1 active galactic nuclei
has remained a major problem for the last two decades. It has not been possible
to distinguish alternative models for the soft excess emission despite the
excellent data quality provided by XMM-Newton and Chandra. Here we present
observations of time lags between the soft and hard band X-ray emission and
discuss the implications to the models for the soft excess. We also device a
method to distinguish the models for the soft excess using Suzaku's broadband
capability.
