diff --git a/agent/agent.h b/agent/agent.h
index 2dfbf5cee..89dc46d05 100644
--- a/agent/agent.h
+++ b/agent/agent.h
@@ -168,7 +168,6 @@ struct
 
 
 /* Bit values for the --debug option.  */
-#define DBG_COMMAND_VALUE 1	/* debug commands i/o */
 #define DBG_MPI_VALUE	  2	/* debug mpi details */
 #define DBG_CRYPTO_VALUE  4	/* debug low level crypto */
 #define DBG_MEMORY_VALUE  32	/* debug memory allocation stuff */
@@ -178,7 +177,6 @@ struct
 #define DBG_IPC_VALUE     1024  /* Enable Assuan debugging.  */
 
 /* Test macros for the debug option.  */
-#define DBG_COMMAND (opt.debug & DBG_COMMAND_VALUE)
 #define DBG_CRYPTO  (opt.debug & DBG_CRYPTO_VALUE)
 #define DBG_MEMORY  (opt.debug & DBG_MEMORY_VALUE)
 #define DBG_CACHE   (opt.debug & DBG_CACHE_VALUE)
diff --git a/agent/gpg-agent.c b/agent/gpg-agent.c
index 5e2e4bfd7..f4ed6c5c4 100644
--- a/agent/gpg-agent.c
+++ b/agent/gpg-agent.c
@@ -251,7 +251,6 @@ static ARGPARSE_OPTS opts[] = {
 /* The list of supported debug flags.  */
 static struct debug_flags_s debug_flags [] =
   {
-    { DBG_COMMAND_VALUE, "command"  },
     { DBG_MPI_VALUE    , "mpi"     },
     { DBG_CRYPTO_VALUE , "crypto"  },
     { DBG_MEMORY_VALUE , "memory"  },
@@ -520,10 +519,9 @@ set_debug (void)
   else if (!strcmp (debug_level, "basic") || (numok && numlvl <= 2))
     opt.debug = DBG_IPC_VALUE;
   else if (!strcmp (debug_level, "advanced") || (numok && numlvl <= 5))
-    opt.debug = DBG_IPC_VALUE|DBG_COMMAND_VALUE;
+    opt.debug = DBG_IPC_VALUE;
   else if (!strcmp (debug_level, "expert") || (numok && numlvl <= 8))
-    opt.debug = (DBG_IPC_VALUE|DBG_COMMAND_VALUE
-                 |DBG_CACHE_VALUE);
+    opt.debug = (DBG_IPC_VALUE | DBG_CACHE_VALUE);
   else if (!strcmp (debug_level, "guru") || numok)
     {
       opt.debug = ~0;
diff --git a/common/miscellaneous.c b/common/miscellaneous.c
index 992494332..c9889750b 100644
--- a/common/miscellaneous.c
+++ b/common/miscellaneous.c
@@ -480,6 +480,8 @@ gnupg_compare_version (const char *a, const char *b)
  *          supplied variable is updated by the parsed flags.
  *
  * If STRING is NULL the enabled debug flags are printed.
+ *
+ * See doc/DETAILS for a summary of used debug options.
  */
 int
 parse_debug_flag (const char *string, unsigned int *debugvar,
diff --git a/dirmngr/dirmngr.c b/dirmngr/dirmngr.c
index ef30d2c3c..0d896f1ef 100644
--- a/dirmngr/dirmngr.c
+++ b/dirmngr/dirmngr.c
@@ -257,6 +257,8 @@ static struct debug_flags_s debug_flags [] =
     { DBG_MEMSTAT_VALUE, "memstat" },
     { DBG_HASHING_VALUE, "hashing" },
     { DBG_IPC_VALUE    , "ipc"     },
+    { DBG_DNS_VALUE    , "dns"     },
+    { DBG_NETWORK_VALUE, "network" },
     { DBG_LOOKUP_VALUE , "lookup"  },
     { 77, NULL } /* 77 := Do not exit on "help" or "?".  */
   };
diff --git a/dirmngr/dirmngr.h b/dirmngr/dirmngr.h
index da1c4beff..9a8787842 100644
--- a/dirmngr/dirmngr.h
+++ b/dirmngr/dirmngr.h
@@ -136,19 +136,23 @@ struct
 
 #define DBG_X509_VALUE    1	/* debug x.509 parsing */
 #define DBG_CRYPTO_VALUE  4	/* debug low level crypto */
+#define DBG_DNS_VALUE     16    /* debug DNS calls.  */
 #define DBG_MEMORY_VALUE  32	/* debug memory allocation stuff */
 #define DBG_CACHE_VALUE   64	/* debug the caching */
 #define DBG_MEMSTAT_VALUE 128	/* show memory statistics */
 #define DBG_HASHING_VALUE 512	/* debug hashing operations */
 #define DBG_IPC_VALUE     1024  /* debug assuan communication */
+#define DBG_NETWORK_VALUE 2048  /* debug network I/O.  */
 #define DBG_LOOKUP_VALUE  8192  /* debug lookup details */
 
 #define DBG_X509    (opt.debug & DBG_X509_VALUE)
 #define DBG_CRYPTO  (opt.debug & DBG_CRYPTO_VALUE)
+#define DBG_DNS     (opt.debug & DBG_DNS_VALUE)
 #define DBG_MEMORY  (opt.debug & DBG_MEMORY_VALUE)
 #define DBG_CACHE   (opt.debug & DBG_CACHE_VALUE)
 #define DBG_HASHING (opt.debug & DBG_HASHING_VALUE)
 #define DBG_IPC     (opt.debug & DBG_IPC_VALUE)
+#define DBG_NETWORK (opt.debug & DBG_NETWORK_VALUE)
 #define DBG_LOOKUP  (opt.debug & DBG_LOOKUP_VALUE)
 
 /* A simple list of certificate references. */
diff --git a/doc/DETAILS b/doc/DETAILS
index 00b55c51b..568500e51 100644
--- a/doc/DETAILS
+++ b/doc/DETAILS
@@ -1328,6 +1328,43 @@ Status codes are:
 
 
 
+* Debug flags
+
+This tables gives the flag values for the --debug option along with
+the alternative names used by the components.
+
+|       | gpg     | gpgsm   | agent   | scd     | dirmngr | g13     | wks     |
+|-------+---------+---------+---------+---------+---------+---------+---------|
+|     1 | packet  | x509    |         |         | x509    | mount   | mime    |
+|     2 | mpi     | mpi     | mpi     | mpi     |         |         | parser  |
+|     4 | crypto  | crypto  | crypto  | crypto  | crypto  | crypto  | crypto  |
+|     8 | filter  |         |         |         |         |         |         |
+|    16 | iobuf   |         |         |         | dns     |         |         |
+|    32 | memory  | memory  | memory  | memory  | memory  | memory  | memory  |
+|    64 | cache   | cache   | cache   | cache   | cache   |         |         |
+|   128 | memstat | memstat | memstat | memstat | memstat | memstat | memstat |
+|   256 | trust   |         |         |         |         |         |         |
+|   512 | hashing | hashing | hashing | hashing | hashing |         |         |
+|  1024 | ipc     | ipc     | ipc     | ipc     | ipc     | ipc     | ipc     |
+|  2048 |         |         |         | cardio  | network |         |         |
+|  4096 | clock   |         |         | reader  |         |         |         |
+|  8192 | lookup  |         |         |         | lookup  |         |         |
+| 16384 | extprog |         |         |         |         |         | extprog |
+
+Description of some debug flags:
+
+  - cardio :: Used by scdaemon to trace the APDUs exchange with the
+              card.
+  - clock  :: Show execution times of certain functions.
+  - crypto :: Trace crypto operations.
+  - hashing :: Create files with the hashed data.
+  - ipc :: Trace the Assuan commands.
+  - mpi :: Show the values of the MPIs.
+  - reader :: Used by scdaemon to trace card reader related code.  For
+              example: Open and close reader.
+
+
+
 * Miscellaneous notes
 
 ** v3 fingerprints
diff --git a/g10/gpg.c b/g10/gpg.c
index a8f731b02..8c5b50589 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -913,7 +913,6 @@ static struct debug_flags_s debug_flags [] =
     { DBG_MEMSTAT_VALUE, "memstat" },
     { DBG_TRUST_VALUE  , "trust"   },
     { DBG_HASHING_VALUE, "hashing" },
-    { DBG_CARD_IO_VALUE, "cardio"  },
     { DBG_IPC_VALUE    , "ipc"     },
     { DBG_CLOCK_VALUE  , "clock"   },
     { DBG_LOOKUP_VALUE , "lookup"  },
diff --git a/g10/options.h b/g10/options.h
index 2449042f5..589b68e1e 100644
--- a/g10/options.h
+++ b/g10/options.h
@@ -300,7 +300,6 @@ struct {
 #define DBG_TRUST_VALUE   256	/* debug the trustdb */
 #define DBG_HASHING_VALUE 512	/* debug hashing operations */
 #define DBG_IPC_VALUE     1024  /* debug assuan communication */
-#define DBG_CARD_IO_VALUE 2048  /* debug smart card I/O.  */
 #define DBG_CLOCK_VALUE   4096
 #define DBG_LOOKUP_VALUE  8192	/* debug the key lookup */
 #define DBG_EXTPROG_VALUE 16384 /* debug external program calls */
@@ -314,7 +313,6 @@ struct {
 #define DBG_TRUST  (opt.debug & DBG_TRUST_VALUE)
 #define DBG_HASHING (opt.debug & DBG_HASHING_VALUE)
 #define DBG_IPC     (opt.debug & DBG_IPC_VALUE)
-#define DBG_CARD_IO (opt.debug & DBG_CARD_IO_VALUE)
 #define DBG_IPC     (opt.debug & DBG_IPC_VALUE)
 #define DBG_CLOCK   (opt.debug & DBG_CLOCK_VALUE)
 #define DBG_LOOKUP  (opt.debug & DBG_LOOKUP_VALUE)
diff --git a/scd/scdaemon.c b/scd/scdaemon.c
index 064cae9cb..38e3c40c4 100644
--- a/scd/scdaemon.c
+++ b/scd/scdaemon.c
@@ -165,7 +165,6 @@ static ARGPARSE_OPTS opts[] = {
 /* The list of supported debug flags.  */
 static struct debug_flags_s debug_flags [] =
   {
-    { DBG_COMMAND_VALUE, "command"  },
     { DBG_MPI_VALUE    , "mpi"     },
     { DBG_CRYPTO_VALUE , "crypto"  },
     { DBG_MEMORY_VALUE , "memory"  },
@@ -328,10 +327,9 @@ set_debug (const char *level)
   else if (!strcmp (level, "basic") || (numok && numlvl <= 2))
     opt.debug = DBG_IPC_VALUE;
   else if (!strcmp (level, "advanced") || (numok && numlvl <= 5))
-    opt.debug = DBG_IPC_VALUE|DBG_COMMAND_VALUE;
+    opt.debug = DBG_IPC_VALUE;
   else if (!strcmp (level, "expert") || (numok && numlvl <= 8))
-    opt.debug = (DBG_IPC_VALUE|DBG_COMMAND_VALUE
-                 |DBG_CACHE_VALUE|DBG_CARD_IO_VALUE);
+    opt.debug = (DBG_IPC_VALUE|DBG_CACHE_VALUE|DBG_CARD_IO_VALUE);
   else if (!strcmp (level, "guru") || numok)
     {
       opt.debug = ~0;
diff --git a/scd/scdaemon.h b/scd/scdaemon.h
index 31e9c791c..38aa4905b 100644
--- a/scd/scdaemon.h
+++ b/scd/scdaemon.h
@@ -65,7 +65,6 @@ struct
 } opt;
 
 
-#define DBG_COMMAND_VALUE 1	/* debug commands i/o */
 #define DBG_MPI_VALUE	  2	/* debug mpi details */
 #define DBG_CRYPTO_VALUE  4	/* debug low level crypto */
 #define DBG_MEMORY_VALUE  32	/* debug memory allocation stuff */
@@ -76,7 +75,6 @@ struct
 #define DBG_CARD_IO_VALUE 2048
 #define DBG_READER_VALUE  4096  /* Trace reader related functions.  */
 
-#define DBG_COMMAND (opt.debug & DBG_COMMAND_VALUE)
 #define DBG_CRYPTO  (opt.debug & DBG_CRYPTO_VALUE)
 #define DBG_MEMORY  (opt.debug & DBG_MEMORY_VALUE)
 #define DBG_CACHE   (opt.debug & DBG_CACHE_VALUE)