diff --git a/utils/man/scoutfs-corruption.7 b/utils/man/scoutfs-corruption.7
index 99e797b3..32ea5a49 100644
--- a/utils/man/scoutfs-corruption.7
+++ b/utils/man/scoutfs-corruption.7
@@ -163,6 +163,52 @@ than the last child reference's key.
 .BR cmp " - comparison of search key and found"
 .sp
 
+.TP
+.B SC_EXTENT_ADD_CLEANUP, SC_EXTENT_REM_CLEANUP, SC_DATA_EXTENT_TRUNC_CLEANUP, SC_DATA_EXTENT_ALLOC_CLEANUP, SC_SERVER_EXTENT_CLEANUP
+
+Extents are used to track regions of blocks or files.  The process of
+modifying an extent creates and destroys intermediate extents, for
+example as two disjoint extents are merged with a third that is created
+between the two.   If an error occurs during this process the
+intermediate extents must be returned to the original state.  If an
+error occurs during this cleanup process then the resulting extents,
+taken as a whole, can be inconsistent.
+
+They can describe overlapping regions. They can forget a region that was
+previously described.  The consequences of these inconsistencies depend
+on the extent type.
+
+The
+.I
+_EXTENT_
+cases occur as core library code is modifying extents.  It can happen on
+behalf of both file data extents and free extents and while adding or
+removing extents.
+
+The
+.I
+_DATA_EXTENT_
+cases occur in file mapping extents while either truncating (removing)
+extents from a file or while allocating extents for a newly written
+region of a file.
+
+The
+.I
+_SERVER_EXTENT_
+case occurs as the server is tracking free extents on behalf of all
+nodes.
+
+Each corruption type message describes the extent and operation.
+
+.BR clean " - extent that was being cleaned up after an error"
+.br
+.BR ext " - primary extent that was being operated on before the error"
+.br
+.BR ret " - negative errno of the first error encountered"
+.br
+.BR op " - the operation the server was performing on the extent"
+.sp
+
 .SH AUTHORS
 Zach Brown <zab@versity.com>
 
diff --git a/utils/src/format.h b/utils/src/format.h
index a4acbed9..f9a33b83 100644
--- a/utils/src/format.h
+++ b/utils/src/format.h
@@ -617,6 +617,11 @@ enum {
 	SC_BTREE_BLOCK_LEVEL,
 	SC_BTREE_NO_CHILD_REF,
 	SC_INODE_BLOCK_COUNTS,
+	SC_EXTENT_ADD_CLEANUP,
+	SC_EXTENT_REM_CLEANUP,
+	SC_DATA_EXTENT_TRUNC_CLEANUP,
+	SC_DATA_EXTENT_ALLOC_CLEANUP,
+	SC_SERVER_EXTENT_CLEANUP,
 	SC_NR_SOURCES,
 };