  This paper describes the intense software filtering that has allowed the
arXiv eprint repository to sort and process large numbers of submissions with
minimal human intervention, making it one of the most important and influential
cases of open access repositories to date. The paper narrates arXiv's
transformation, using sophisticated sorting-filtering algorithms to decrease
human workload, from a small mailing list used by a few hundred researchers to
a site that processes thousands of papers per month. However there are
significant negative consequences for authors who have been filtered out of the
main categories. There is thus a continued need to check and balance arXiv's
boundaries, based in the essential tension between stability and innovation.
