This is advisory only, but likely to save on system-calls and packets
sent when a sequence of calls to the function are made.
-The argument was added in Exim version 4.90 - changing the API.
-Nobody noticed until 4.93 was imminent.
-A decision on the way forward has not yet been made.
+The argument was added in Exim version 4.90 - changing the API/ABI.
+Nobody noticed until 4.93 was imminent, at which point the
+ABI version number was incremented.
.wen
Strings that are written by &'smtp_printf()'& from within &[local_scan()]&