Add footnote with BUSL antecedents

Thanks to Chad Whitacre for pointing these out.

dosp-survey.ltx

 ---
 title: "Delayed Open Source Publication:\\\\A Survey of Historical and Current Practices"
-date: 30 Nov 2023
+date: TBD (after 2023-11-30 publication of v1)
 ---
 
 %% extends "report.ltx"
@@ -497,7 +497,17 @@ The Business Source License (BUSL; sometimes ``BSL''\footnote{Most
 originally written in 2016 by MariaDB for its MaxScale project.  The
 current version of BUSL, 1.1, was released in 2017 and first used for
 MaxScale 2.1.0.\footnote{See
-  \otsurl{https://mariadb.com/resources/blog/releasing-bsl-1-1/}.}
+  \otsurl{https://mariadb.com/resources/blog/releasing-bsl-1-1/}.
+  There is at least one earlier proposal of the concept: the ``Open
+  Source Eventually License'', described in 2016 (see
+  \otsurl{https://github.com/ftrotter/OSE/tree/a360875170b4a9818e3a4691beced81d7d5f13a8}).
+  It is fundamentally the same idea as BUSL, but precedes the BUSL by
+  at least a few months.  A more tenuous antecedant comes from Richard
+  Stallman, in
+  \otsurl{https://www.gnu.org/philosophy/netscape-npl.html}, in the
+  section ``Not all users are equal'', which proposes that the harms
+  of asymmetrical licensing could be reduced by putting a time limit
+  on the asymmetry.}
 
 BUSL requires a licensor to specify a ``Change Date'' and a ``Change
 License''.  On the Change Date, which is some time in the future, the