The Super String, sometimes also referred to as Future-Proof String is a String File with lots of custom strings like wrestler names, title names, etc. to be used for mods in various WWE 2k games created by LordJustice17 and Pozzum with the help of Caveman, kim666 and others.
When you install new modded characters part of the install involves injecting a .pofo file. .pofo files contain all the character info (height, weight, etc). Inside the .pofo is an ID which points to a string (strings are just bits of text) for the character's name as it will appear in-game.
The Super String has thousands of added names. Meaning that almost everyone who will be created already has a name string included, so you won't have to edit your string file. Additionally, the Super String provides a bit of universality so that .pofo and .attire_names creators know what IDs to use that will work for everyone.
LordJustice17 created the Future Proof String for WWE 2k16 to be future proofed for future mods by replacing unused Strings in the file with names for custom mods. Since it didn't turn out to be exactly future proof as originally intended, it was renamed to Super String for the WWE 2k17 version. With the help of Pozzum, kim666 and Caveman, they succeeded in internally separating the game string from custom strings and add a sub-file for tons of additional custom strings so it isn't necessary to replace existing strings anymore. LordJustice17 with the help of Pozzum, Perfectplex and others created a Super String for WWE 2k18. Sadly the separation of the game string from custom strings is no longer possible due to WWE 2k18 limitations and they had to delete several game Strings to make room for more modded Strings this year (note that this limitation doesn't exist as much in WWE 2k19, however).
The Super String has also been included in several Modding Tools for various games that support it, including Data Editor, CCT and WrestlePlus, some of these programs have convenient installers that will install the SuperString for you.
Super String for WWE 2k19
Super String for WWE 2k18
Super String for WWE 2k17
Future-Proof String for WWE 2k16
This is the Super String for WWE 2k16.