diff --git a/lib/cmdline/cmdline.go b/lib/cmdline/cmdline.go
index 82c032c..74245f2 100644
--- a/lib/cmdline/cmdline.go
+++ b/lib/cmdline/cmdline.go
@@ -18,6 +18,7 @@
 	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"strings"
 )
@@ -51,6 +52,9 @@
 	// child's name, and call Run on the first matching child.
 	Children []*Command
 
+	// Topics that provide additional info via the default help command.
+	Topics []Topic
+
 	// Run is a function that runs cmd with args.  If both Children and Run are
 	// specified, Run will only be called if none of the children match.  It is an
 	// error if neither is specified.  The special ErrExitCode error may be
@@ -76,6 +80,14 @@
 	//   Alias map[string]string
 }
 
+// Topic represents an additional help topic that is accessed via the default
+// help command.
+type Topic struct {
+	Name  string // Name of the topic.
+	Short string // Short description, shown in help for the command.
+	Long  string // Long description, shown in help for this topic.
+}
+
 // style describes the formatting style for usage descriptions.
 type style int
 
@@ -126,106 +138,123 @@
 	fmt.Fprint(cmd.stderr, "ERROR: ")
 	fmt.Fprintf(cmd.stderr, format, v...)
 	fmt.Fprint(cmd.stderr, "\n\n")
-	cmd.usage(cmd.stderr, styleText, true)
+	cmd.usage(cmd.stderr, true)
 	return ErrUsage
 }
 
-// usage prints the usage of cmd to the writer, with the given style.  The
-// firstCall boolean is set to false when printing usage for multiple commands,
-// and is used to avoid printing redundant information (e.g. section headers,
-// global flags).
-func (cmd *Command) usage(w io.Writer, style style, firstCall bool) {
-	var names []string
-	for c := cmd; c != nil; c = c.parent {
-		names = append([]string{c.Name}, names...)
-	}
-	namestr := strings.Join(names, " ")
-	if !firstCall && style == styleGoDoc {
-		// Title-case names so that godoc recognizes it as a section header.
-		fmt.Fprintf(w, "%s\n\n", strings.Title(namestr))
-	}
-	// Long description.
-	fmt.Fprint(w, strings.Trim(cmd.Long, "\n"))
-	fmt.Fprintln(w)
+// usage prints the usage of cmd to the writer.  The firstCall boolean is set to
+// false when printing usage for multiple commands, and is used to avoid
+// printing redundant information (e.g. help command, global flags).
+func (cmd *Command) usage(w io.Writer, firstCall bool) {
+	printLong(w, cmd.Long)
 	// Usage line.
-	hasFlags := false
-	cmd.Flags.VisitAll(func(*flag.Flag) {
-		hasFlags = true
-	})
+	hasFlags := numFlags(&cmd.Flags) > 0
 	fmt.Fprintf(w, "\nUsage:\n")
-	nameflags := "   " + namestr
+	path := namePath(cmd)
+	pathf := "   " + path
 	if hasFlags {
-		nameflags += " [flags]"
+		pathf += " [flags]"
 	}
 	if len(cmd.Children) > 0 {
-		fmt.Fprintf(w, "%s <command>\n", nameflags)
+		fmt.Fprintf(w, "%s <command>\n", pathf)
 	}
 	if cmd.Run != nil {
 		if cmd.ArgsName != "" {
-			fmt.Fprintf(w, "%s %s\n", nameflags, cmd.ArgsName)
+			fmt.Fprintf(w, "%s %s\n", pathf, cmd.ArgsName)
 		} else {
-			fmt.Fprintf(w, "%s\n", nameflags)
+			fmt.Fprintf(w, "%s\n", pathf)
 		}
 	}
 	if len(cmd.Children) == 0 && cmd.Run == nil {
 		// This is a specification error.
-		fmt.Fprintf(w, "%s [ERROR: neither Children nor Run is specified]\n", nameflags)
+		fmt.Fprintf(w, "%s [ERROR: neither Children nor Run is specified]\n", pathf)
 	}
 	// Commands.
 	if len(cmd.Children) > 0 {
 		fmt.Fprintf(w, "\nThe %s commands are:\n", cmd.Name)
 		for _, child := range cmd.Children {
-			if !firstCall && child.isDefaultHelp {
-				continue // don't repeatedly list default help command
+			// Don't repeatedly list default help command.
+			if !child.isDefaultHelp || firstCall {
+				fmt.Fprintf(w, "   %-11s %s\n", child.Name, child.Short)
 			}
-			fmt.Fprintf(w, "   %-11s %s\n", child.Name, child.Short)
+		}
+		if firstCall {
+			fmt.Fprintf(w, "Run \"%s help [command]\" for command usage.\n", path)
 		}
 	}
 	// Args.
 	if cmd.Run != nil && cmd.ArgsLong != "" {
-		fmt.Fprintf(w, "\n")
-		fmt.Fprint(w, strings.Trim(cmd.ArgsLong, "\n"))
-		fmt.Fprintf(w, "\n")
+		fmt.Fprintln(w)
+		printLong(w, cmd.ArgsLong)
+	}
+	// Help topics.
+	if len(cmd.Topics) > 0 {
+		fmt.Fprintf(w, "\nThe %s additional help topics are:\n", cmd.Name)
+		for _, topic := range cmd.Topics {
+			fmt.Fprintf(w, "   %-11s %s\n", topic.Name, topic.Short)
+		}
+		if firstCall {
+			fmt.Fprintf(w, "Run \"%s help [topic]\" for topic details.\n", path)
+		}
 	}
 	// Flags.
 	if hasFlags {
 		fmt.Fprintf(w, "\nThe %s flags are:\n", cmd.Name)
-		cmd.Flags.VisitAll(func(f *flag.Flag) {
-			fmt.Fprintf(w, "   -%s=%s: %s\n", f.Name, f.DefValue, f.Usage)
-		})
+		printFlags(w, &cmd.Flags)
 	}
 	// Global flags.
-	hasGlobalFlags := false
-	flag.VisitAll(func(*flag.Flag) {
-		hasGlobalFlags = true
-	})
-	if firstCall && hasGlobalFlags {
+	if numFlags(flag.CommandLine) > 0 && firstCall {
 		fmt.Fprintf(w, "\nThe global flags are:\n")
-		flag.VisitAll(func(f *flag.Flag) {
-			fmt.Fprintf(w, "   -%s=%s: %s\n", f.Name, f.DefValue, f.Usage)
-		})
+		printFlags(w, flag.CommandLine)
 	}
 }
 
+// namePath returns the path of command names up to cmd.
+func namePath(cmd *Command) string {
+	var path []string
+	for ; cmd != nil; cmd = cmd.parent {
+		path = append([]string{cmd.Name}, path...)
+	}
+	return strings.Join(path, " ")
+}
+
+func printLong(w io.Writer, long string) {
+	fmt.Fprint(w, strings.Trim(long, "\n"))
+	fmt.Fprintln(w)
+}
+
+func numFlags(set *flag.FlagSet) (num int) {
+	set.VisitAll(func(*flag.Flag) {
+		num++
+	})
+	return
+}
+
+func printFlags(w io.Writer, set *flag.FlagSet) {
+	set.VisitAll(func(f *flag.Flag) {
+		fmt.Fprintf(w, "   -%s=%s: %s\n", f.Name, f.DefValue, f.Usage)
+	})
+}
+
 // newDefaultHelp creates a new default help command.  We need to create new
 // instances since the parent for each help command is different.
 func newDefaultHelp() *Command {
 	helpStyle := styleText
 	help := &Command{
 		Name:  helpName,
-		Short: "Display help for commands",
+		Short: "Display help for commands or topics",
 		Long: `
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 `,
-		ArgsName: "[command ...]",
+		ArgsName: "[command/topic ...]",
 		ArgsLong: `
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 `,
 		Run: func(cmd *Command, args []string) error {
 			// Help applies to its parent - e.g. "foo help" applies to the foo command.
-			return runHelp(cmd.parent, args, helpStyle)
+			return runHelp(cmd.stdout, cmd.parent, args, helpStyle)
 		},
 		isDefaultHelp: true,
 	}
@@ -236,57 +265,63 @@
 const helpName = "help"
 
 // runHelp runs the "help" command.
-func runHelp(cmd *Command, args []string, style style) error {
+func runHelp(w io.Writer, cmd *Command, args []string, style style) error {
 	if len(args) == 0 {
-		cmd.usage(cmd.stdout, style, true)
+		cmd.usage(w, true)
 		return nil
 	}
 	if args[0] == "..." {
-		recursiveHelp(cmd, style, true)
+		recursiveHelp(w, cmd, style, true)
 		return nil
 	}
-	// Find the subcommand to display help.
-	subName := args[0]
-	subArgs := args[1:]
+	// Try to display help for the subcommand.
+	subName, subArgs := args[0], args[1:]
 	for _, child := range cmd.Children {
 		if child.Name == subName {
-			return runHelp(child, subArgs, style)
+			return runHelp(w, child, subArgs, style)
 		}
 	}
-	return cmd.UsageErrorf("%s: unknown command %q", cmd.Name, subName)
+	// Try to display help for the help topic.
+	for _, topic := range cmd.Topics {
+		if topic.Name == subName {
+			printLong(w, topic.Long)
+			return nil
+		}
+	}
+	return cmd.UsageErrorf("%s: unknown command or topic %q", cmd.Name, subName)
 }
 
 // recursiveHelp prints help recursively via DFS from this cmd onward.
-func recursiveHelp(cmd *Command, style style, firstCall bool) {
-	cmd.usage(cmd.stdout, style, firstCall)
+func recursiveHelp(w io.Writer, cmd *Command, style style, firstCall bool) {
+	if !firstCall {
+		// Title-case required for godoc to recognize this as a section header.
+		header := strings.Title(namePath(cmd))
+		lineBreak(w, style)
+		fmt.Fprintf(w, "%s\n\n", header)
+	}
+	cmd.usage(w, firstCall)
+	for _, child := range cmd.Children {
+		// Don't repeatedly print default help command.
+		if !child.isDefaultHelp || firstCall {
+			recursiveHelp(w, child, style, false)
+		}
+	}
+	for _, topic := range cmd.Topics {
+		// Title-case required for godoc to recognize this as a section header.
+		header := strings.Title(namePath(cmd) + " " + topic.Name + " (Help Topic)")
+		lineBreak(w, style)
+		fmt.Fprintf(w, "%s\n\n", header)
+		printLong(w, topic.Long)
+	}
+}
+
+func lineBreak(w io.Writer, style style) {
 	switch style {
 	case styleText:
-		fmt.Fprintln(cmd.stdout, strings.Repeat("=", 80))
+		fmt.Fprintln(w, strings.Repeat("=", 80))
 	case styleGoDoc:
-		fmt.Fprintln(cmd.stdout)
+		fmt.Fprintln(w)
 	}
-	for _, child := range cmd.Children {
-		if !firstCall && child.isDefaultHelp {
-			continue // don't repeatedly print default help command
-		}
-		recursiveHelp(child, style, false)
-	}
-}
-
-// prefixErrorWriter simply wraps a regular io.Writer and adds an "ERROR: "
-// prefix if Write is ever called.  It's used to ensure errors are clearly
-// marked when flag.FlagSet.Parse encounters errors.
-type prefixErrorWriter struct {
-	writer        io.Writer
-	prefixWritten bool
-}
-
-func (p *prefixErrorWriter) Write(b []byte) (int, error) {
-	if !p.prefixWritten {
-		io.WriteString(p.writer, "ERROR: ")
-		p.prefixWritten = true
-	}
-	return p.writer.Write(b)
 }
 
 // Init initializes all nodes in the command tree rooted at cmd.  Init must be
@@ -306,38 +341,48 @@
 	if !hasHelp && cmd.Name != helpName && len(cmd.Children) > 0 {
 		cmd.Children = append(cmd.Children, newDefaultHelp())
 	}
-	// Merge command-specific and global flags into parseFlags.
+	// Merge command-specific and global flags into parseFlags.  We want to handle
+	// all error output ourselves, so we:
+	//   1) Set flag.ContinueOnError so that Parse() doesn't exit or panic.
+	//   2) Discard all output (can't be nil, that means stderr).
+	//   3) Set an empty Usage function (can't be nil, that means default).
 	cmd.parseFlags = flag.NewFlagSet(cmd.Name, flag.ContinueOnError)
-	cmd.parseFlags.SetOutput(&prefixErrorWriter{writer: stderr})
-	cmd.parseFlags.Usage = func() {
-		cmd.usage(stderr, styleText, true)
-	}
-	flagMerger := func(f *flag.Flag) {
-		if cmd.parseFlags.Lookup(f.Name) == nil {
-			cmd.parseFlags.Var(f.Value, f.Name, f.Usage)
-		}
-	}
-	cmd.Flags.VisitAll(flagMerger)
-	flag.VisitAll(flagMerger)
+	cmd.parseFlags.SetOutput(ioutil.Discard)
+	cmd.parseFlags.Usage = emptyUsage
+	mergeFlags(cmd.parseFlags, &cmd.Flags)
+	mergeFlags(cmd.parseFlags, flag.CommandLine)
 	// Call children recursively.
 	for _, child := range cmd.Children {
 		child.Init(cmd, stdout, stderr)
 	}
 }
 
+func mergeFlags(dst, src *flag.FlagSet) {
+	src.VisitAll(func(f *flag.Flag) {
+		if dst.Lookup(f.Name) == nil {
+			dst.Var(f.Value, f.Name, f.Usage)
+		}
+	})
+}
+
+func emptyUsage() {}
+
 // Execute the command with the given args.  The returned error is ErrUsage if
 // there are usage errors, otherwise it is whatever the leaf command returns
 // from its Run function.
 func (cmd *Command) Execute(args []string) error {
 	// Parse the merged flags.
 	if err := cmd.parseFlags.Parse(args); err != nil {
-		return ErrUsage
+		if err == flag.ErrHelp {
+			cmd.usage(cmd.stdout, true)
+			return nil
+		}
+		return cmd.UsageErrorf(err.Error())
 	}
 	args = cmd.parseFlags.Args()
 	// Look for matching children.
 	if len(args) > 0 {
-		subName := args[0]
-		subArgs := args[1:]
+		subName, subArgs := args[0], args[1:]
 		for _, child := range cmd.Children {
 			if child.Name == subName {
 				return child.Execute(subArgs)
@@ -349,9 +394,8 @@
 		if cmd.ArgsName == "" && len(args) > 0 {
 			if len(cmd.Children) > 0 {
 				return cmd.UsageErrorf("%s: unknown command %q", cmd.Name, args[0])
-			} else {
-				return cmd.UsageErrorf("%s doesn't take any arguments", cmd.Name)
 			}
+			return cmd.UsageErrorf("%s doesn't take any arguments", cmd.Name)
 		}
 		return cmd.Run(cmd, args)
 	}
@@ -374,9 +418,8 @@
 	if err := cmd.Execute(os.Args[1:]); err != nil {
 		if code, ok := err.(ErrExitCode); ok {
 			os.Exit(int(code))
-		} else {
-			fmt.Fprintf(os.Stderr, "ERROR: %v\n", err)
-			os.Exit(2)
 		}
+		fmt.Fprintf(os.Stderr, "ERROR: %v\n", err)
+		os.Exit(2)
 	}
 }
diff --git a/lib/cmdline/cmdline_test.go b/lib/cmdline/cmdline_test.go
index f4a424c..255f1d5 100644
--- a/lib/cmdline/cmdline_test.go
+++ b/lib/cmdline/cmdline_test.go
@@ -177,7 +177,8 @@
 
 The onecmd commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "onecmd help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -196,7 +197,8 @@
 
 The onecmd commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "onecmd help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -212,7 +214,8 @@
 
 The onecmd commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "onecmd help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -235,14 +238,14 @@
 		},
 		{
 			Args: []string{"help", "help"},
-			Stdout: `Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+			Stdout: `Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   onecmd help [flags] [command ...]
+   onecmd help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
@@ -261,12 +264,15 @@
 
 The onecmd commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "onecmd help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Onecmd Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -274,24 +280,25 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Onecmd Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   onecmd help [flags] [command ...]
+   onecmd help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
 			Args: []string{"help", "foo"},
 			Err:  ErrUsage,
-			Stderr: `ERROR: onecmd: unknown command "foo"
+			Stderr: `ERROR: onecmd: unknown command or topic "foo"
 
 Onecmd only has the echo command.
 
@@ -300,7 +307,8 @@
 
 The onecmd commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "onecmd help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -383,7 +391,8 @@
 The multi commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "multi help [command]" for command usage.
 
 The multi flags are:
    -extra=false: Print an extra arg
@@ -403,7 +412,8 @@
 The multi commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "multi help [command]" for command usage.
 
 The multi flags are:
    -extra=false: Print an extra arg
@@ -423,7 +433,8 @@
 The multi commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "multi help [command]" for command usage.
 
 The multi flags are:
    -extra=false: Print an extra arg
@@ -432,6 +443,8 @@
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Multi Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -439,6 +452,8 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
+Multi Echoopt
+
 Echoopt prints any args passed in to stdout.
 
 Usage:
@@ -449,18 +464,19 @@
 The echoopt flags are:
    -n=false: Do not output trailing newline
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Multi Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   multi help [flags] [command ...]
+   multi help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
@@ -497,7 +513,7 @@
 		{
 			Args: []string{"help", "foo"},
 			Err:  ErrUsage,
-			Stderr: `ERROR: multi: unknown command "foo"
+			Stderr: `ERROR: multi: unknown command or topic "foo"
 
 Multi has two variants of echo.
 
@@ -507,7 +523,8 @@
 The multi commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "multi help [command]" for command usage.
 
 The multi flags are:
    -extra=false: Print an extra arg
@@ -569,6 +586,7 @@
 			Args: []string{"echo", "-n", "foo", "bar"},
 			Err:  ErrUsage,
 			Stderr: `ERROR: flag provided but not defined: -n
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -585,6 +603,7 @@
 			Args: []string{"-nosuchflag", "echo", "foo", "bar"},
 			Err:  ErrUsage,
 			Stderr: `ERROR: flag provided but not defined: -nosuchflag
+
 Multi has two variants of echo.
 
 Usage:
@@ -593,7 +612,8 @@
 The multi commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "multi help [command]" for command usage.
 
 The multi flags are:
    -extra=false: Print an extra arg
@@ -646,6 +666,9 @@
 		Short:    "Set of echo commands",
 		Long:     "Echoprog has two variants of echo.",
 		Children: []*Command{cmdEcho, cmdEchoOpt},
+		Topics: []Topic{
+			{Name: "topic3", Short: "Help topic 3 short", Long: "Help topic 3 long."},
+		},
 	}
 	echoProg.Flags.BoolVar(&flagExtra, "extra", false, "Print an extra arg")
 	prog := &Command{
@@ -653,6 +676,10 @@
 		Short:    "Top level prog",
 		Long:     "Toplevelprog has the echo subprogram and the hello command.",
 		Children: []*Command{echoProg, cmdHello},
+		Topics: []Topic{
+			{Name: "topic1", Short: "Help topic 1 short", Long: "Help topic 1 long."},
+			{Name: "topic2", Short: "Help topic 2 short", Long: "Help topic 2 long."},
+		},
 	}
 	prog.Flags.BoolVar(&flagTopLevelExtra, "tlextra", false, "Print an extra arg for all commands")
 
@@ -670,7 +697,13 @@
 The toplevelprog commands are:
    echoprog    Set of echo commands
    hello       Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog help [command]" for command usage.
+
+The toplevelprog additional help topics are:
+   topic1      Help topic 1 short
+   topic2      Help topic 2 short
+Run "toplevelprog help [topic]" for topic details.
 
 The toplevelprog flags are:
    -tlextra=false: Print an extra arg for all commands
@@ -690,7 +723,13 @@
 The toplevelprog commands are:
    echoprog    Set of echo commands
    hello       Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog help [command]" for command usage.
+
+The toplevelprog additional help topics are:
+   topic1      Help topic 1 short
+   topic2      Help topic 2 short
+Run "toplevelprog help [topic]" for topic details.
 
 The toplevelprog flags are:
    -tlextra=false: Print an extra arg for all commands
@@ -710,7 +749,13 @@
 The toplevelprog commands are:
    echoprog    Set of echo commands
    hello       Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog help [command]" for command usage.
+
+The toplevelprog additional help topics are:
+   topic1      Help topic 1 short
+   topic2      Help topic 2 short
+Run "toplevelprog help [topic]" for topic details.
 
 The toplevelprog flags are:
    -tlextra=false: Print an extra arg for all commands
@@ -719,6 +764,8 @@
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Toplevelprog Echoprog
+
 Echoprog has two variants of echo.
 
 Usage:
@@ -728,9 +775,14 @@
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
 
+The echoprog additional help topics are:
+   topic3      Help topic 3 short
+
 The echoprog flags are:
    -extra=false: Print an extra arg
 ================================================================================
+Toplevelprog Echoprog Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -738,6 +790,8 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
+Toplevelprog Echoprog Echoopt
+
 Echoopt prints any args passed in to stdout.
 
 Usage:
@@ -748,6 +802,12 @@
 The echoopt flags are:
    -n=false: Do not output trailing newline
 ================================================================================
+Toplevelprog Echoprog Topic3 (Help Topic)
+
+Help topic 3 long.
+================================================================================
+Toplevelprog Hello
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -755,18 +815,27 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Toplevelprog Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   toplevelprog help [flags] [command ...]
+   toplevelprog help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
 ================================================================================
+Toplevelprog Topic1 (Help Topic)
+
+Help topic 1 long.
+================================================================================
+Toplevelprog Topic2 (Help Topic)
+
+Help topic 2 long.
 `,
 		},
 		{
@@ -779,7 +848,12 @@
 The echoprog commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog echoprog help [command]" for command usage.
+
+The echoprog additional help topics are:
+   topic3      Help topic 3 short
+Run "toplevelprog echoprog help [topic]" for topic details.
 
 The echoprog flags are:
    -extra=false: Print an extra arg
@@ -790,6 +864,16 @@
 `,
 		},
 		{
+			Args: []string{"help", "topic1"},
+			Stdout: `Help topic 1 long.
+`,
+		},
+		{
+			Args: []string{"help", "topic2"},
+			Stdout: `Help topic 2 long.
+`,
+		},
+		{
 			Args: []string{"echoprog", "help", "..."},
 			Stdout: `Echoprog has two variants of echo.
 
@@ -799,7 +883,12 @@
 The echoprog commands are:
    echo        Print strings on stdout
    echoopt     Print strings on stdout, with opts
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog echoprog help [command]" for command usage.
+
+The echoprog additional help topics are:
+   topic3      Help topic 3 short
+Run "toplevelprog echoprog help [topic]" for topic details.
 
 The echoprog flags are:
    -extra=false: Print an extra arg
@@ -808,6 +897,8 @@
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Toplevelprog Echoprog Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -815,6 +906,8 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
+Toplevelprog Echoprog Echoopt
+
 Echoopt prints any args passed in to stdout.
 
 Usage:
@@ -825,18 +918,23 @@
 The echoopt flags are:
    -n=false: Do not output trailing newline
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Toplevelprog Echoprog Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   toplevelprog echoprog help [flags] [command ...]
+   toplevelprog echoprog help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
 ================================================================================
+Toplevelprog Echoprog Topic3 (Help Topic)
+
+Help topic 3 long.
 `,
 		},
 		{
@@ -857,6 +955,16 @@
 `,
 		},
 		{
+			Args: []string{"help", "echoprog", "topic3"},
+			Stdout: `Help topic 3 long.
+`,
+		},
+		{
+			Args: []string{"echoprog", "help", "topic3"},
+			Stdout: `Help topic 3 long.
+`,
+		},
+		{
 			Args: []string{"help", "hello"},
 			Stdout: `Hello prints any strings passed in to stdout preceded by "Hello".
 
@@ -873,7 +981,7 @@
 		{
 			Args: []string{"help", "foo"},
 			Err:  ErrUsage,
-			Stderr: `ERROR: toplevelprog: unknown command "foo"
+			Stderr: `ERROR: toplevelprog: unknown command or topic "foo"
 
 Toplevelprog has the echo subprogram and the hello command.
 
@@ -883,7 +991,13 @@
 The toplevelprog commands are:
    echoprog    Set of echo commands
    hello       Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog help [command]" for command usage.
+
+The toplevelprog additional help topics are:
+   topic1      Help topic 1 short
+   topic2      Help topic 2 short
+Run "toplevelprog help [topic]" for topic details.
 
 The toplevelprog flags are:
    -tlextra=false: Print an extra arg for all commands
@@ -941,6 +1055,7 @@
 			Args: []string{"hello", "--extra", "foo", "bar"},
 			Err:  ErrUsage,
 			Stderr: `ERROR: flag provided but not defined: -extra
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -957,6 +1072,7 @@
 			Args: []string{"-extra", "echoprog", "echoopt", "foo", "bar"},
 			Err:  ErrUsage,
 			Stderr: `ERROR: flag provided but not defined: -extra
+
 Toplevelprog has the echo subprogram and the hello command.
 
 Usage:
@@ -965,7 +1081,13 @@
 The toplevelprog commands are:
    echoprog    Set of echo commands
    hello       Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "toplevelprog help [command]" for command usage.
+
+The toplevelprog additional help topics are:
+   topic1      Help topic 1 short
+   topic2      Help topic 2 short
+Run "toplevelprog help [topic]" for topic details.
 
 The toplevelprog flags are:
    -tlextra=false: Print an extra arg for all commands
@@ -1074,7 +1196,8 @@
    hello11     Print strings on stdout preceded by "Hello"
    hello12     Print strings on stdout preceded by "Hello"
    prog2       Set of hello commands
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -1092,7 +1215,8 @@
    hello11     Print strings on stdout preceded by "Hello"
    hello12     Print strings on stdout preceded by "Hello"
    prog2       Set of hello commands
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -1110,12 +1234,15 @@
    hello11     Print strings on stdout preceded by "Hello"
    hello12     Print strings on stdout preceded by "Hello"
    prog2       Set of hello commands
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Prog1 Hello11
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1123,6 +1250,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Hello12
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1130,6 +1259,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2
+
 Prog2 has two variants of hello and a subprogram prog3.
 
 Usage:
@@ -1140,6 +1271,8 @@
    prog3       Set of hello commands
    hello22     Print strings on stdout preceded by "Hello"
 ================================================================================
+Prog1 Prog2 Hello21
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1147,6 +1280,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3
+
 Prog3 has two variants of hello.
 
 Usage:
@@ -1156,6 +1291,8 @@
    hello31     Print strings on stdout preceded by "Hello"
    hello32     Print strings on stdout preceded by "Hello"
 ================================================================================
+Prog1 Prog2 Prog3 Hello31
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1163,6 +1300,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3 Hello32
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1170,6 +1309,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Hello22
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1177,18 +1318,19 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Prog1 Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   prog1 help [flags] [command ...]
+   prog1 help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
@@ -1202,12 +1344,15 @@
    hello21     Print strings on stdout preceded by "Hello"
    prog3       Set of hello commands
    hello22     Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 prog2 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Prog1 Prog2 Hello21
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1215,6 +1360,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3
+
 Prog3 has two variants of hello.
 
 Usage:
@@ -1224,6 +1371,8 @@
    hello31     Print strings on stdout preceded by "Hello"
    hello32     Print strings on stdout preceded by "Hello"
 ================================================================================
+Prog1 Prog2 Prog3 Hello31
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1231,6 +1380,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3 Hello32
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1238,6 +1389,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Hello22
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1245,18 +1398,19 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Prog1 Prog2 Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   prog1 prog2 help [flags] [command ...]
+   prog1 prog2 help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
@@ -1269,12 +1423,15 @@
 The prog3 commands are:
    hello31     Print strings on stdout preceded by "Hello"
    hello32     Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 prog2 prog3 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Prog1 Prog2 Prog3 Hello31
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1282,6 +1439,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3 Hello32
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1289,18 +1448,19 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Prog1 Prog2 Prog3 Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   prog1 prog2 prog3 help [flags] [command ...]
+   prog1 prog2 prog3 help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
@@ -1313,12 +1473,15 @@
 The prog3 commands are:
    hello31     Print strings on stdout preceded by "Hello"
    hello32     Print strings on stdout preceded by "Hello"
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 prog2 prog3 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Prog1 Prog2 Prog3 Hello31
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1326,6 +1489,8 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
+Prog1 Prog2 Prog3 Hello32
+
 Hello prints any strings passed in to stdout preceded by "Hello".
 
 Usage:
@@ -1333,18 +1498,19 @@
 
 [strings] are arbitrary strings that will be printed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Prog1 Prog2 Prog3 Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   prog1 prog2 prog3 help [flags] [command ...]
+   prog1 prog2 prog3 help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
@@ -1358,7 +1524,8 @@
    hello11     Print strings on stdout preceded by "Hello"
    hello12     Print strings on stdout preceded by "Hello"
    prog2       Set of hello commands
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "prog1 help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -1443,18 +1610,17 @@
 
 Prog1 Help
 
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   prog1 help [flags] [command ...]
+   prog1 help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-
 `,
 		},
 	}
@@ -1503,7 +1669,8 @@
 
 The cmdargs commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdargs help [command]" for command usage.
 
 [strings] are arbitrary strings that will be printed.
 
@@ -1536,7 +1703,8 @@
 
 The cmdargs commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdargs help [command]" for command usage.
 
 [strings] are arbitrary strings that will be printed.
 
@@ -1544,6 +1712,8 @@
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Cmdargs Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -1551,24 +1721,25 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Cmdargs Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   cmdargs help [flags] [command ...]
+   cmdargs help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
 			Args: []string{"help", "foo"},
 			Err:  ErrUsage,
-			Stderr: `ERROR: cmdargs: unknown command "foo"
+			Stderr: `ERROR: cmdargs: unknown command or topic "foo"
 
 Cmdargs has the echo command and a Run function with args.
 
@@ -1578,7 +1749,8 @@
 
 The cmdargs commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdargs help [command]" for command usage.
 
 [strings] are arbitrary strings that will be printed.
 
@@ -1654,7 +1826,8 @@
 
 The cmdrun commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdrun help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -1671,7 +1844,8 @@
 
 The cmdrun commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdrun help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
@@ -1702,12 +1876,15 @@
 
 The cmdrun commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdrun help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1
    -global2=0: global test flag 2
 ================================================================================
+Cmdrun Echo
+
 Echo prints any strings passed in to stdout.
 
 Usage:
@@ -1715,24 +1892,25 @@
 
 [strings] are arbitrary strings that will be echoed.
 ================================================================================
-Help displays usage descriptions for this command, or usage descriptions for
-sub-commands.
+Cmdrun Help
+
+Help with no args displays the usage of the parent command.
+Help with args displays the usage of the specified sub-command or help topic.
+"help ..." recursively displays help for all commands and topics.
 
 Usage:
-   cmdrun help [flags] [command ...]
+   cmdrun help [flags] [command/topic ...]
 
-[command ...] is an optional sequence of commands to display detailed usage.
-The special-case "help ..." recursively displays help for all commands.
+[command/topic ...] optionally identifies a specific sub-command or help topic.
 
 The help flags are:
    -style=text: The formatting style for help output, either "text" or "godoc".
-================================================================================
 `,
 		},
 		{
 			Args: []string{"help", "foo"},
 			Err:  ErrUsage,
-			Stderr: `ERROR: cmdrun: unknown command "foo"
+			Stderr: `ERROR: cmdrun: unknown command or topic "foo"
 
 Cmdrun has the echo command and a Run function with no args.
 
@@ -1742,7 +1920,8 @@
 
 The cmdrun commands are:
    echo        Print strings on stdout
-   help        Display help for commands
+   help        Display help for commands or topics
+Run "cmdrun help [command]" for command usage.
 
 The global flags are:
    -global1=: global test flag 1