add some windows documentation and comments

README.WINDOWS

@@ -0,0 +1,28 @@
+Platform-specific notes: windows
+================================
+
+For more information please see https://dev.pep.foundation/Windows .
+
+
+Character encoding
+------------------
+
+It is important that we can emit Unicode output.
+
+Internal memory
+...............
+The p≡p Engine works internally using UTF-8 strings
+
+Console
+.......
+The p≡p Engine always prints to the console in UTF-8.
+
+It is the user's responsibility to configure the console.
+
+Other output
+............
+In every other contexts on this platform, including system logs, the
+output is in wide chars: we treat that as if it were UTF-16, ignoring
+the difference between UTF-16 and UCS-2.
+
+This is achieved using -W functions.

src/pEp_log.h

@@ -169,7 +169,18 @@ typedef enum {
          sqlite> SELECT * FROM UserEntries;  */
     PEP_LOG_DESTINATION_DATABASE  =   4,
 
-    /* Send log entries to the syslog service. */
+    /* Send log entries to the syslog service, or (on windows) on the native log
+       destination obtained from OpenEventLogW -- windows logging is implemented
+       as an emulated syslog API. */
+    /*
+      https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-openeventlogw
+      OpenEventLogW
+      example: https://learn.microsoft.com/en-us/windows/win32/eventlog/querying-for-event-source-messages
+
+      ReportEvent
+      example: https://learn.microsoft.com/en-us/windows/win32/eventlog/reporting-an-event
+      */
+
     PEP_LOG_DESTINATION_SYSLOG    =   8,
 
     /* Use the Android logging system. */