diff --git a/src/xz/xz.1 b/src/xz/xz.1
index f4680f49..3ff89f00 100644
--- a/src/xz/xz.1
+++ b/src/xz/xz.1
@@ -1874,6 +1874,25 @@ headers.
 .PD
 .PP
 The columns of the
+.B summary
+lines:
+.PD 0
+.RS
+.IP 2. 4
+Amount of memory (in bytes) required to decompress
+this file with this
+.B xz
+version
+.IP 3. 4
+.B yes
+or
+.B no
+indicating if all block headers have both compressed size and
+uncompressed size stored in them
+.RE
+.PD
+.PP
+The columns of the
 .B totals
 line:
 .PD 0