(I know that there are plenty of my users out there who will back me up on this in private, but I'd quite appreciate it if they did so publicly.) I do not use diagrams intensively, and for occasional use I found Paul's macros very useful and easy to remember. They also serve well to draw non-categorical diagrams (like Church-Rosser diagrams, Barendregt's cube , etc). I have to admit that I am a bit surprised that Michael Barr proposes something like: \diagram(4,4) \object(1,1){TT} \object(2,1)T \object(2,2){TTT'} ..... \arrow(1,1)(2,2)_{TT\eta'} \arrow(1,1)(2,1)_\mu \twoarrow(2,2)(3,2)_{T\sigma}^{\mu T} ... \enddiagram First of all I don't want to calculate positions and I don't want (and can) remember the names of lots of different objects (like 'Vtriangle'). Actually I haven't used Barr's package and it may well be that these macros are better suited for a very intensive user of categorical diagrams. However, I would rather appreciate it if there is a standard for diagrams acceptable for a wider class of users. Thorsten Altenkirch Kennst du das Land, wo die Zitronen blu"hn, Laboratory for Foundations Im dunkeln Laub die Gold-Orangen glu"hn, of Computer Science Ein sanfter Wind vom blauen Himmel weht, Die Myrte still und hoch der Lorbeer steht, University of Edinburgh Kennst du es wohl? Dahin! Dahin Mo"cht ich mit dir, o mein Geliebter, ziehn. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++