Index: lib/libc/gen/sysctlnametomib.c
===================================================================
--- lib/libc/gen/sysctlnametomib.c
+++ lib/libc/gen/sysctlnametomib.c
@@ -47,8 +47,8 @@
 	int oid[2];
 	int error;
 
-	oid[0] = 0;
-	oid[1] = 3;
+	oid[0] = CTL_SYSCTL;
+	oid[1] = CTL_SYSCTL_NAME2OID;
 
 	*sizep *= sizeof(int);
 	error = sysctl(oid, 2, mibp, sizep, name, strlen(name));
Index: sys/kern/kern_sysctl.c
===================================================================
--- sys/kern/kern_sysctl.c
+++ sys/kern/kern_sysctl.c
@@ -935,13 +935,18 @@
  * (be aware though, that the proper interface isn't as obvious as it
  * may seem, there are various conflicting requirements.
  *
- * {0,0}	printf the entire MIB-tree.
- * {0,1,...}	return the name of the "..." OID.
- * {0,2,...}	return the next OID.
- * {0,3}	return the OID of the name in "new"
- * {0,4,...}	return the kind & format info for the "..." OID.
- * {0,5,...}	return the description of the "..." OID.
- * {0,6,...}	return the aggregation label of the "..." OID.
+ * {CTL_SYSCTL, CTL_SYSCTL_DEBUG}		printf the entire MIB-tree.
+ * {CTL_SYSCTL, CTL_SYSCTL_NAME,...}		return the name of the "..."
+ *						OID.
+ * {CTL_SYSCTL, CTL_SYSCTL_NEXT,...}		return the next OID.
+ * {CTL_SYSCTL, CTL_SYSCTL_NAME2OID}		return the OID of the name in
+ *						"new"
+ * {CTL_SYSCTL, CTL_SYSCTL_OIDFMT,...}		return the kind & format info
+ *						for the "..." OID.
+ * {CTL_SYSCTL, CTL_SYSCTL_OIDDESCR,...}	return the description of the
+ *						"..." OID.
+ * {CTL_SYSCTL, CTL_SYSCTL_OIDLABEL,...}	return the aggregation label of
+ *						the "..." OID.
  */
 
 #ifdef SYSCTL_DEBUG
@@ -1009,8 +1014,8 @@
 	return (ENOENT);
 }
 
-SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
-	0, 0, sysctl_sysctl_debug, "-", "");
+SYSCTL_PROC(_sysctl, CTL_SYSCTL_DEBUG, debug, CTLTYPE_STRING | CTLFLAG_RD |
+    CTLFLAG_MPSAFE, 0, 0, sysctl_sysctl_debug, "-", "");
 #endif
 
 static int
@@ -1075,8 +1080,8 @@
  * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
  * capability mode.
  */
-static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
-    sysctl_sysctl_name, "");
+static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NAME, name, CTLFLAG_RD |
+    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_name, "");
 
 static int
 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
@@ -1162,8 +1167,8 @@
  * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
  * capability mode.
  */
-static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
-    sysctl_sysctl_next, "");
+static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NEXT, next, CTLFLAG_RD |
+    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_next, "");
 
 static int
 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
@@ -1249,9 +1254,9 @@
  * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
  * capability mode.
  */
-SYSCTL_PROC(_sysctl, 3, name2oid,
-    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE
-    | CTLFLAG_CAPRW, 0, 0, sysctl_sysctl_name2oid, "I", "");
+SYSCTL_PROC(_sysctl, CTL_SYSCTL_NAME2OID, name2oid, CTLTYPE_INT | CTLFLAG_RW |
+    CTLFLAG_ANYBODY | CTLFLAG_MPSAFE | CTLFLAG_CAPRW, 0, 0,
+    sysctl_sysctl_name2oid, "I", "");
 
 static int
 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
@@ -1279,8 +1284,8 @@
 }
 
 
-static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
-    sysctl_sysctl_oidfmt, "");
+static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDFMT, oidfmt, CTLFLAG_RD |
+    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidfmt, "");
 
 static int
 sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
@@ -1304,8 +1309,8 @@
 	return (error);
 }
 
-static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
-    sysctl_sysctl_oiddescr, "");
+static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDDESCR, oiddescr, CTLFLAG_RD |
+    CTLFLAG_MPSAFE|CTLFLAG_CAPRD, sysctl_sysctl_oiddescr, "");
 
 static int
 sysctl_sysctl_oidlabel(SYSCTL_HANDLER_ARGS)
@@ -1329,8 +1334,8 @@
 	return (error);
 }
 
-static SYSCTL_NODE(_sysctl, 6, oidlabel,
-    CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidlabel, "");
+static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDLABEL, oidlabel, CTLFLAG_RD |
+    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidlabel, "");
 
 /*
  * Default "handler" functions.
@@ -1857,8 +1862,8 @@
         size_t oidlen, plen;
 	int error;
 
-	oid[0] = 0;		/* sysctl internal magic */
-	oid[1] = 3;		/* name2oid */
+	oid[0] = CTL_SYSCTL;
+	oid[1] = CTL_SYSCTL_NAME2OID;
 	oidlen = sizeof(oid);
 
 	error = kernel_sysctl(td, oid, 2, oid, &oidlen,
@@ -2165,8 +2170,8 @@
 	if (error != 0)
 		goto out;
 
-	oid[0] = 0;
-	oid[1] = 3;
+	oid[0] = CTL_SYSCTL;
+	oid[1] = CTL_SYSCTL_NAME2OID;
 	oidlen = sizeof(oid);
 	error = kernel_sysctl(td, oid, 2, oid, &oidlen, (void *)name, namelen,
 	    retval, flags);
@@ -2667,8 +2672,8 @@
 	int name1[CTL_MAXNAME + 2], name2[CTL_MAXNAME + 2];
 	size_t l1, l2;
 
-	name1[0] = 0;
-	name1[1] = 2;
+	name1[0] = CTL_SYSCTL;
+	name1[1] = CTL_SYSCTL_NEXT;
 	l1 = 2;
 	if (len) {
 		memcpy(name1+2, oid, len * sizeof(int));
Index: sys/sys/sysctl.h
===================================================================
--- sys/sys/sysctl.h
+++ sys/sys/sysctl.h
@@ -889,7 +889,7 @@
 /*
  * Top-level identifiers
  */
-#define	CTL_UNSPEC	0		/* unused */
+#define	CTL_SYSCTL	0		/* "magic" numbers */
 #define	CTL_KERN	1		/* "high kernel": proc, limits */
 #define	CTL_VM		2		/* virtual memory */
 #define	CTL_VFS		3		/* filesystem, mount type is next */
@@ -901,6 +901,17 @@
 #define	CTL_P1003_1B	9		/* POSIX 1003.1B */
 
 /*
+ * CTL_SYSCTL identifiers
+ */
+#define	CTL_SYSCTL_DEBUG	0	/* printf all nodes */
+#define	CTL_SYSCTL_NAME		1	/* string name of OID */
+#define	CTL_SYSCTL_NEXT		2	/* next OID */
+#define	CTL_SYSCTL_NAME2OID	3	/* int array of name */
+#define	CTL_SYSCTL_OIDFMT	4	/* OID's kind and format */
+#define	CTL_SYSCTL_OIDDESCR	5	/* OID's description */
+#define	CTL_SYSCTL_OIDLABEL	6	/* aggregation label */
+
+/*
  * CTL_KERN identifiers
  */
 #define	KERN_OSTYPE		 1	/* string: system version */