This template works in the background to support Template:Version and Template:UseCase. It displays a table field, explaining, for which railML® version a page is written. It compares that string with the current version number deposed in Template:Current and reports, whether the content can be considered to be up to date or not.
As to support the maintanance of this wiki, the template categorizes pages, in which it is included, according to the version number for which they have been written. Thus pages that are up to date can be found in category:Pages written for version 2.5.
The only, unnamed and default argument of this template is the version number for which a page has been written.