+# c) fsl ends the escape sequence begun by tsl. Printable characters between
+# those (probably) will appear in the window title. Nonprintable characters
+# may cause the escape sequence to end with an error.
+# d) the BEL (^G or \007) used in the original title-as-statusline came from
+# David J. MacKenzie's "pseudo-color" entry in 20 Apr 1995. At that time
+# xterm used BEL as the string-terminator rather than ST (\E\\). Either
+# BEL or ST has worked since xterm patch #28 in 1996, but most uses of
+# this feature have been embedded in shell scripts.
+#
+# But that issue regarding the parameter for tsl means that applications may
+# not rely on it. The SVr4 documentation says tsl will "move to status line,
+# column #1". At the point in time when ESR added DJM's "pseudo-color" entry
+# with the split-up escape sequence for tsl/fsl, there were 65 entries using
+# tsl:
+# 32 used a parameter, matching the documentation (including x10term).
+# 21 used a parameterless control, exiting from the status line on ^M.
+# 6 used parameterless controls for tsl and fsl
+# 6 used a split-up escape sequence, e.g., the same approach.