+repeatable: Either 0 or 1 to indicate if autorepeat is allowed.
+
+command: Pointer to the command function. This is the function that is
+ called when the command is issued.
+
+usage: Short description. This is a string.
+
+help: Long description. This is a string. The long description is
+ only available if CONFIG_SYS_LONGHELP is defined.
+
+comp: Pointer to the completion function. May be NULL.
+ This function is called if the user hits the TAB key while
+ entering the command arguments to complete the entry. Command
+ completion is only available if CONFIG_AUTO_COMPLETE is defined.
+
+Command function
+----------------
+
+The commmand function pointer has to be of type
+int (*cmd)(struct cmd_tbl_s *cmdtp, int flag, int argc, const char *argv[]);
+
+cmdtp: Table entry describing the command (see above).
+
+flag: A bitmap which may contain the following bit:
+ CMD_FLAG_REPEAT - The last command is repeated.
+ CMD_FLAG_BOOTD - The command is called by the bootd command.
+ CMD_FLAG_ENV - The command is called by the run command.
+
+argc: Number of arguments including the command.
+
+argv: Arguments.
+
+Allowable return value are:
+
+CMD_SUCCESS The command was successfully executed.
+
+CMD_FAILURE The command failed.
+
+CMD_RET_USAGE The command was called with invalid parameters. This value
+ leads to the display of the usage string.
+
+Completion function
+-------------------
+
+The completion function pointer has to be of type
+int (*complete)(int argc, char *const argv[], char last_char,
+ int maxv, char *cmdv[]);
+
+argc: Number of arguments including the command.
+
+argv: Arguments.
+
+last_char: The last character in the command line buffer.
+
+maxv: Maximum number of possible completions that may be returned by
+ the function.
+
+cmdv: Used to return possible values for the last argument. The last
+ possible completion must be followed by NULL.
+
+The function returns the number of possible completions (without the terminating
+NULL value).
+
+Behind the scene
+----------------