The fan communities that generate fan fiction are quite serious about their work.
For those who dismiss the work as either either the writing of fringe "geeks" with no real talent or education or else just the shoddy stories of bored teens or unemployed young adults...Well, that probably does apply to some of the population, but, by and large, the fan community is full of talented and aspiring writers who are serious about the fan fiction they create and the larger community of fan fiction writers that they are a part of.
OneStone32 and those who respond to him are discussing the importance of labelling techniques in archiving fan fiction stories. The art of archiving shows the importance this fan community sees in their work as an extension to "official" content in a fictional series or else as a body of work all in its own, an official canon of work in a particular film series.
This type of information--the labels for what a story or group of stories is--is the paratext, and labeling what a story is and what it means to the stories that surrounds it is an important part of not only "legitimate" published writing but fan fiction as well.
Be sure to view this metacommentary on the art and rules of fan fiction, especially for anyone not well associated with the online world of fan fiction writing.