This is a tracking category, a category intended to build and maintain a list of pages primarily for the sake of the list itself. These categories are used to track, for example, pages using deprecated syntaxes, to maintain a list of pages that may need to be edited en masse later, or to aggregate the members of several sub-categories by other classifications into one larger list.
These pages are part of theAdministration of the TrainzWikibook project.This category lists pages of Trainz needing maintenance fix ups of a stubbed in but missing url. Trainz, as a software suite has been around a long time now, and the occasional 3rd-party reference sometimes have changed.
Pages are automatically added to this category when the Template:TrainzLinkNeeded is used to note the presence of such an 'unfixed link' (orphaned, moved, different isp, etc.) when using the Plain link template and testing the link fails to find a valid url. Use of the Template: TrainzLinkNeeded let's the editor stay focused on prose, and deffer finding an alternative link, if one exists at all anymore.
Old url references requiring fixes can be preserved by prefixing the bad url with '|3=' as documented in the template. This can aid in finding a lost page referenced if the task is deferred.
Template: TrainzLinkNeeded is just a version of {{Plain link}} which substitutes for a bad or missing url the message providing Template:Trainz_Link_Needed as a full url as a default.
Given a proper first argument of type url as the first argument ({{{1}}}), the template will operate precisely as {{plain link|{{{1}}}|{{{2}}}}} call does and continue to try linking a bad url whilst correctly categorize the page as needing link maintenance.
Optionally, given a broken link:
Argument {{{1}}} of the TrainzLinkNeeded template can be a Null argument: {{TrainzLinkNeeded || Intended Link Title}}
(note: the BOLD double ' || ' pipes argument separators).
The page-fix needed is simply replacing a token url with a proper url link as the first argument of Template:Plain link.
Page fixes, then involve hunting down the proper url edited in as argument {{{1}}}, and replacing {{TrainzLinkNeeded}} with {{plain link}} in the calling line.
When fixed (by an valid and tested 'plain link' reference) then the page will no longer need to include this category, which should normally be empty.
