There has been released March 2013 Public Updates for SharePoint 2013. In somehow, they are like the February 2013 CU + some extra updates
Please, they are mandatory in order to install next April 2013 and onward CUs.
If you have a farm with search component and high availability search topologies enabled; you should follow next entry:
If you are installed in SharePoint Server 2013 bear in mind that the server one includes the foundation. It’s not needed to install foundation.
Furthemore, if you have any server running Workflow Manager and Service Bus, their Cus are also available:
Héctor Calvarro Martín. SharePoint Dev/Core. Microsoft Support Escalation Engineer for EMEA