A DSMB or Delayed Surface Marker Buoy works the same as a SMB but it is inflated and deployed from underwater. It is composed of a surface marker buoy secured by a line on a spool or by a WDS. DSMB allow a diver to be located and spotted from the surface while still being at desired depth. It helps in preventing and avoiding accidents with boats and is considered mandatory in many places.
The dive tables were invented to deal with the effect of surrounding pressure that increase the nitrogen dissolved in our body. They were the first way to calculate times and depths to dive safely and prevent decompression sicknesses. Nowadays computers applies almost real time the calculations made to create the tables.
A Safety Stop or SS is a stop or pause that divers do at the end of a recreational dive before surfacing. They are not required in the case of an emergency but are very good practices to help prevent the onset of decompression sicknesses. They are done at 5 meters for a period of 3 minutes.