diff -r 10305c5b0a16 -r 4853fbad5014 dav/sync.h
--- a/dav/sync.h	Wed May 30 16:25:57 2018 +0200
+++ b/dav/sync.h	Wed May 30 16:49:25 2018 +0200
@@ -118,6 +118,8 @@
  */
 typedef struct SyncTagFilter SyncTagFilter;
 
+/* OFF must be zero, other constants are arbitrary */
+#define DAV_SYNC_TAGFILTER_OFF     0
 #define DAV_SYNC_TAGFILTER_AND     1
 #define DAV_SYNC_TAGFILTER_OR      2
 #define DAV_SYNC_TAGFILTER_ONE     3