Overview of SQL Server Reporting Services 2012 Architecture, Features, and Tools - Learning SQL Server Reporting Services 2012 - page 148

Deploying (which amounts to saving) a report developed using Report Builder
to SharePoint Server is a lot easier as the process is interactive as shown in the
next image that displays the server and folders while saving a report to a
SharePoint Server.
Report validation
Reports created in SSDT are validated before preview and during deployment. If
there are several elements some of them may get skipped because they are up to date
and need no verification. Error level property is used to manage build warnings and
errors and they run from 0 to 4. The default Build ErrorLevel is set to 2 , which means
it is less severe, but may change layout drastically. Build errors may crop up due to
several reasons and are written to the output window. The following screenshot is
taken from the project's property pages shows the error levels.