Bison 3.7 was recently released, with the accompanying release notes containing this snippet:
In conformance with the recommendations of the Graphviz team, in the next
version Bison the option--graph
will generate a *.gv file by default,
instead of *.dot. A transition started in Bison 3.4.
I thought this was interesting because (1) I had no idea Bison could generate Graphviz and (2) I did not realize .gv was preferred over .dot. Maybe these are widely known to others.
The recommendation seems to have come on a mailing list thread, pointing to a Wikipedia page, pointing to Emden’s recommendation in 2011.