CAUTION: The Sender of this email is not from within Dalhousie. Mateo Carmona has made (with the collaboration of Ulrik Buchholtz) an extended and revised version of: Pursuing stacks https://github.com/thescrivener/PursuingStacks Originally written between February 1983 and January 1984 represents a very important moment in the development of Grothendieck, namely that of "le nouveau style". You can see it here: https://agrothendieck.github.io/divers/ps.pdf Relevant to this work is also a note written in 1968 called "Tapis de Quillen" https://agrothendieck.github.io/divers/tapisQscan.pdf (and a project of transcription https://agrothendieck.github.io/divers/tapisQ.pdf) Remarks, and corrections, in general, are welcome. If you want to see more, please visit and get involved in https://agrothendieck.github.io/ David Roberts Webpage: https://ncatlab.org/nlab/show/David+Roberts Blog: https://thehighergeometer.wordpress.com [For admin and other information see: http://www.mta.ca/~cat-dist/ ]