TagScripts project is available in GN4 build 1.6.1970.x or newer.
It is added to the standard GN4AddinsExpress solution with the name TagScripts.
By default, the TagScripts project contains the Editions.vb with Public class Editions and several functions, whereas the WriteEditionDate gets called in the schema addition. This is however, just an example. You can add your own functions to the Editions.vb and then add the appropriate calls to the schema, to make them available to the >writes...< tag, used on master pages.
Important: the schema additions and the scripts must correspond!
After you compiled the GN4 solution, you need to deploy the TagScripts.dll to specific folders. This is explained in Compile add-ins solution and deploy TagScripts.dll.