SVRS stands for Statewide Voter Registration System. It was implemented as part of HAVA - the Help America Vote Act, which was passed in 2002. The idea was that states would modernize by having an electronic voter registration database that would help keep the registration system up to date.
In actuality it has created an online database that is easy to hack and manipulate as we saw happen in both the primaries and the general election of 2016. And because you can affect who gets to vote by changing the voter registration database, you can affect the outcome of the election by manipulating the database as well.
Here is the link to the description of Wisconsin's Statewide Voter Registration database.
"Statewide Voter Registration System (SVRS): This database represents Wisconsin’s compliance with the federal Help America Vote Act (HAVA) of 2002 to have a single, uniform, official, centralized, and interactive computer statewide voter registration list. SVRS contains the name and registration information of every registered voter in the state and also provides the ability to record and track voter participation."
Demonstrating yet again that there is more than a little irony in the name "Help America Vote Act."