Jiri B pointed out that /var/cache is undocumented;

sthen provided the description

1 files changed, 4 insertions, 2 deletions

diff --git a/share/man/man7/hier.7 b/share/man/man7/hier.7
index dc349bfdc48..78eb3dfcde1 100644
--- a/share/man/man7/hier.7
+++ b/share/man/man7/hier.7
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: hier.7,v 1.106 2012/12/09 18:21:44 jmc Exp $
+.\"	$OpenBSD: hier.7,v 1.107 2013/06/10 12:42:05 jmc Exp $
 .\"	$NetBSD: hier.7,v 1.7 1994/11/30 19:07:10 jtc Exp $
 .\"
 .\" Copyright (c) 1990, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"	@(#)hier.7	8.1 (Berkeley) 6/5/93
 .\"
-.Dd $Mdocdate: December 9 2012 $
+.Dd $Mdocdate: June 10 2013 $
 .Dt HIER 7
 .Os
 .Sh NAME
@@ -569,6 +569,8 @@ PID file for
 .Xr authpf 8 .
 .It backups/
 Miscellaneous backup files.
+.It cache/
+Data cached for programs.
 .It crash/
 Crash dumps written by
 .Xr savecore 8 .