diff --git a/cmd/gotext/examples/main.go b/cmd/gotext/examples/main.go
index e1a84e0..08ac143 100644
--- a/cmd/gotext/examples/main.go
+++ b/cmd/gotext/examples/main.go
@@ -45,13 +45,16 @@
 	pp := struct {
 		Person string // The person of matter. // TODO: get this comment.
 		Place  string
+		extra  int
 	}{
-		person, place,
+		person, place, 4,
 	}
 
 	// extract will drop this comment in favor of the one below.
-	p.Printf("%s is visiting %s!\n", // Person visiting a place.
+	// argument is added as a placeholder.
+	p.Printf("%[1]s is visiting %[3]s!\n", // Person visiting a place.
 		pp.Person,
+		pp.extra,
 		pp.Place, // Place the person is visiting.
 	)
 
@@ -76,4 +79,8 @@
 	const msgOutOfOrder = "%s is out of order!" // FOO
 	const device = "Soda machine"
 	p.Printf(msgOutOfOrder, device)
+
+	// Double arguments.
+	miles := 1.2345
+	p.Printf("%.2[1]f miles traveled (%[1]f)", miles)
 }
diff --git a/cmd/gotext/examples/textdata/gotext_en.out.json b/cmd/gotext/examples/textdata/gotext_en.out.json
index e6ebe5d..3dd943a 100755
--- a/cmd/gotext/examples/textdata/gotext_en.out.json
+++ b/cmd/gotext/examples/textdata/gotext_en.out.json
@@ -15,17 +15,14 @@
         "message": {
             "msg": "Hello {City}!\n"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "City",
-                "argNum": 1,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[1]s",
                 "type": "string",
                 "underlyingType": "string",
-                "expr": "city",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:31:26"
+                "argNum": 1,
+                "expr": "city"
             }
         ],
         "position": "golang.org/x/text/cmd/gotext/examples/main.go:31:10"
@@ -37,18 +34,15 @@
         "message": {
             "msg": "Hello {Town}!\n"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "Town",
-                "argNum": 1,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[1]s",
                 "type": "string",
                 "underlyingType": "string",
+                "argNum": 1,
                 "expr": "town",
-                "comment": "Town",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:36:3"
+                "comment": "Town"
             }
         ],
         "position": "golang.org/x/text/cmd/gotext/examples/main.go:35:10"
@@ -60,68 +54,64 @@
         "message": {
             "msg": "{Person} is visiting {Place}!\n"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "Person",
-                "argNum": 1,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[1]s",
                 "type": "string",
                 "underlyingType": "string",
+                "argNum": 1,
                 "expr": "person",
-                "comment": "The person of matter.",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:41:3"
+                "comment": "The person of matter."
             },
             {
                 "id": "Place",
-                "argNum": 2,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[2]s",
                 "type": "string",
                 "underlyingType": "string",
+                "argNum": 2,
                 "expr": "place",
-                "comment": "Place the person is visiting.",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:42:3"
+                "comment": "Place the person is visiting."
             }
         ],
         "position": "golang.org/x/text/cmd/gotext/examples/main.go:40:10"
     },
     {
         "key": [
-            "%s is visiting %s!\n"
+            "%[1]s is visiting %[3]s!\n"
         ],
         "message": {
             "msg": "{Person} is visiting {Place}!\n"
         },
         "comment": "Person visiting a place.",
-        "args": [
+        "placeholders": [
             {
                 "id": "Person",
-                "argNum": 1,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[1]s",
                 "type": "string",
                 "underlyingType": "string",
-                "expr": "pp.Person",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:54:3"
+                "argNum": 1,
+                "expr": "pp.Person"
             },
             {
                 "id": "Place",
-                "argNum": 2,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[3]s",
                 "type": "string",
                 "underlyingType": "string",
+                "argNum": 3,
                 "expr": "pp.Place",
-                "comment": "Place the person is visiting.",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:55:3"
+                "comment": "Place the person is visiting."
+            },
+            {
+                "id": "Extra",
+                "string": "%[2]v",
+                "type": "int",
+                "underlyingType": "int",
+                "argNum": 2,
+                "expr": "pp.extra"
             }
         ],
-        "position": "golang.org/x/text/cmd/gotext/examples/main.go:53:10"
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:55:10"
     },
     {
         "key": [
@@ -130,21 +120,17 @@
         "message": {
             "msg": "{2} files remaining!"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "2",
-                "argNum": 1,
-                "format": [
-                    "%d"
-                ],
+                "string": "%[1]d",
                 "type": "int",
                 "underlyingType": "int",
-                "expr": "2",
-                "value": "2",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:59:34"
+                "argNum": 1,
+                "expr": "2"
             }
         ],
-        "position": "golang.org/x/text/cmd/gotext/examples/main.go:59:10"
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:62:10"
     },
     {
         "key": [
@@ -153,21 +139,17 @@
         "message": {
             "msg": "{N} more files remaining!"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "N",
-                "argNum": 1,
-                "format": [
-                    "%d"
-                ],
+                "string": "%[1]d",
                 "type": "int",
                 "underlyingType": "int",
-                "expr": "n",
-                "value": "2",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:64:39"
+                "argNum": 1,
+                "expr": "n"
             }
         ],
-        "position": "golang.org/x/text/cmd/gotext/examples/main.go:64:10"
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:67:10"
     },
     {
         "key": [
@@ -176,21 +158,17 @@
         "message": {
             "msg": "Use the following code for your discount: {ReferralCode}\n"
         },
-        "args": [
+        "placeholders": [
             {
                 "id": "ReferralCode",
-                "argNum": 1,
-                "format": [
-                    "%d"
-                ],
+                "string": "%[1]d",
                 "type": "golang.org/x/text/cmd/gotext/examples.referralCode",
                 "underlyingType": "int",
-                "expr": "c",
-                "value": "5",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:70:61"
+                "argNum": 1,
+                "expr": "c"
             }
         ],
-        "position": "golang.org/x/text/cmd/gotext/examples/main.go:70:10"
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:73:10"
     },
     {
         "key": [
@@ -201,20 +179,43 @@
             "msg": "{Device} is out of order!"
         },
         "comment": "FOO\n",
-        "args": [
+        "placeholders": [
             {
                 "id": "Device",
-                "argNum": 1,
-                "format": [
-                    "%s"
-                ],
+                "string": "%[1]s",
                 "type": "string",
                 "underlyingType": "string",
-                "expr": "device",
-                "value": "\"Soda machine\"",
-                "position": "golang.org/x/text/cmd/gotext/examples/main.go:78:26"
+                "argNum": 1,
+                "expr": "device"
             }
         ],
-        "position": "golang.org/x/text/cmd/gotext/examples/main.go:78:10"
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:81:10"
+    },
+    {
+        "key": [
+            "%.2[1]f miles traveled (%[1]f)"
+        ],
+        "message": {
+            "msg": "{Miles} miles traveled ({Miles_1})"
+        },
+        "placeholders": [
+            {
+                "id": "Miles",
+                "string": "%.2[1]f",
+                "type": "float64",
+                "underlyingType": "float64",
+                "argNum": 1,
+                "expr": "miles"
+            },
+            {
+                "id": "Miles_1",
+                "string": "%[1]f",
+                "type": "float64",
+                "underlyingType": "float64",
+                "argNum": 1,
+                "expr": "miles"
+            }
+        ],
+        "position": "golang.org/x/text/cmd/gotext/examples/main.go:85:10"
     }
 ]
\ No newline at end of file
diff --git a/cmd/gotext/extract.go b/cmd/gotext/extract.go
index ac318d1..3b6120d 100644
--- a/cmd/gotext/extract.go
+++ b/cmd/gotext/extract.go
@@ -21,6 +21,7 @@
 	"path/filepath"
 	"strings"
 	"unicode"
+	"unicode/utf8"
 
 	fmtparser "golang.org/x/text/internal/format"
 	"golang.org/x/tools/go/loader"
@@ -135,7 +136,7 @@
 				}
 
 				key = append(key, fmtMsg)
-				arguments := []Argument{}
+				arguments := []argument{}
 				args = args[1:]
 				simArgs := make([]interface{}, len(args))
 				for i, arg := range args {
@@ -149,7 +150,7 @@
 							expr = val
 						}
 					}
-					arguments = append(arguments, Argument{
+					arguments = append(arguments, argument{
 						ArgNum:         i + 1,
 						Type:           info.Types[arg].Type.String(),
 						UnderlyingType: info.Types[arg].Type.Underlying().String(),
@@ -164,6 +165,8 @@
 				}
 				msg := ""
 
+				ph := placeholders{index: map[string]string{}}
+
 				p := fmtparser.Parser{}
 				p.Reset(simArgs)
 				for p.SetFormat(fmtMsg); p.Scan(); {
@@ -173,28 +176,37 @@
 					case fmtparser.StatusSubstitution,
 						fmtparser.StatusBadWidthSubstitution,
 						fmtparser.StatusBadPrecSubstitution:
+						arguments[p.ArgNum-1].used = true
 						arg := arguments[p.ArgNum-1]
-						id := getID(&arg)
-						arguments[p.ArgNum-1].ID = id
-						// TODO: do we allow the same entry to be formatted
-						// differently within the same string, do we give
-						// a warning, or is this an error?
-						arguments[p.ArgNum-1].Format = append(arguments[p.ArgNum-1].Format, p.Text())
-						msg += fmt.Sprintf("{%s}", id)
+						sub := p.Text()
+						if !p.HasIndex {
+							r, sz := utf8.DecodeLastRuneInString(sub)
+							sub = fmt.Sprintf("%s[%d]%c", sub[:len(sub)-sz], p.ArgNum, r)
+						}
+						msg += fmt.Sprintf("{%s}", ph.addArg(&arg, sub))
 					}
 				}
 
+				// Add additional Placeholders that can be used in translations
+				// that are not present in the string.
+				for _, arg := range arguments {
+					if arg.used {
+						continue
+					}
+					ph.addArg(&arg, fmt.Sprintf("%%[%d]v", arg.ArgNum))
+				}
+
 				if c := getComment(call.Args[0]); c != "" {
 					comment = c
 				}
 
 				messages = append(messages, Message{
-					Key:      key,
-					Position: posString(conf, info, call.Lparen),
-					Message:  Text{Msg: msg},
+					Key:     key,
+					Message: Text{Msg: msg},
 					// TODO(fix): this doesn't get the before comment.
-					Comment: comment,
-					Args:    arguments,
+					Comment:      comment,
+					Placeholders: ph.slice,
+					Position:     posString(conf, info, call.Lparen),
 				})
 				return true
 			})
@@ -245,7 +257,7 @@
 	arg int
 }
 
-func getID(arg *Argument) string {
+func getID(arg *argument) string {
 	s := getLastComponent(arg.Expr)
 	s = strings.Replace(s, " ", "", -1)
 	// For small variable names, use user-defined types for more info.
@@ -255,6 +267,32 @@
 	return strings.Title(s)
 }
 
+type placeholders struct {
+	index map[string]string
+	slice []Placeholder
+}
+
+func (p *placeholders) addArg(arg *argument, sub string) (id string) {
+	id = getID(arg)
+	id1 := id
+	alt, ok := p.index[id1]
+	for i := 1; ok && alt != sub; i++ {
+		id1 = fmt.Sprintf("%s_%d", id, i)
+		alt, ok = p.index[id1]
+	}
+	p.index[id1] = sub
+	p.slice = append(p.slice, Placeholder{
+		ID:             id1,
+		String:         sub,
+		Type:           arg.Type,
+		UnderlyingType: arg.UnderlyingType,
+		ArgNum:         arg.ArgNum,
+		Expr:           arg.Expr,
+		Comment:        arg.Comment,
+	})
+	return id1
+}
+
 func getLastComponent(s string) string {
 	return s[1+strings.LastIndexByte(s, '.'):]
 }
diff --git a/cmd/gotext/message.go b/cmd/gotext/message.go
index 7344f8d..567cf5d 100644
--- a/cmd/gotext/message.go
+++ b/cmd/gotext/message.go
@@ -28,36 +28,55 @@
 	Comment           string `json:"comment,omitempty"`
 	TranslatorComment string `json:"translatorComment,omitempty"`
 
-	// TODO: have a separate placeholder list, mapping placeholders
-	// to arguments or constant strings.
-	// TODO: default placeholder syntax is {foo}. Allow alternatives
-	// like `foo`.
+	Placeholders []Placeholder `json:"placeholders,omitempty"`
 
-	Args []Argument `json:"args,omitempty"`
+	// TODO: default placeholder syntax is {foo}. Allow alternative escaping
+	// like `foo`.
 
 	// Extraction information.
 	Position string `json:"position,omitempty"` // filePosition:line
 }
 
-// An Argument contains information about the arguments passed to a message.
-type Argument struct {
-	ID string `json:"id"` // An int for printf-style calls, but could be a string.
-	// Argument position for printf-style format strings. ArgNum corresponds to
-	// the number that should be used for explicit argument indexes (e.g.
-	// "%[1]d").
-	ArgNum int      `json:"argNum,omitempty"`
-	Format []string `json:"format,omitempty"`
+// A Placeholder is a part of the message that should not be changed by a
+// translator. It can be used to hide or prettify format strings (e.g. %d or
+// {{.Count}}), hide HTML, or mark common names that should not be translated.
+type Placeholder struct {
+	// ID is the placeholder identifier without the curly braces.
+	ID string `json:"id"`
 
+	// String is the string with which to replace the placeholder. This may be a
+	// formatting string (for instance "%d" or "{{.Count}}") or a literal string
+	// (<div>).
+	String string `json:"string"`
+
+	Type           string `json:"type"`
+	UnderlyingType string `json:"underlyingType"`
+	// ArgNum and Expr are set if the placeholder is a substitution of an
+	// argument.
+	ArgNum int    `json:"argNum,omitempty"`
+	Expr   string `json:"expr,omitempty"`
+
+	Comment string `json:"comment,omitempty"`
+	Example string `json:"example,omitempty"`
+
+	// Features contains the features that are available for the implementation
+	// of this argument.
+	Features []Feature `json:"features,omitempty"`
+}
+
+// An argument contains information about the arguments passed to a message.
+type argument struct {
+	// ArgNum corresponds to the number that should be used for explicit argument indexes (e.g.
+	// "%[1]d").
+	ArgNum int `json:"argNum,omitempty"`
+
+	used           bool   // Used by Placeholder
 	Type           string `json:"type"`
 	UnderlyingType string `json:"underlyingType"`
 	Expr           string `json:"expr"`
 	Value          string `json:"value,omitempty"`
 	Comment        string `json:"comment,omitempty"`
 	Position       string `json:"position,omitempty"`
-
-	// Features contains the features that are available for the implementation
-	// of this argument.
-	Features []Feature `json:"features,omitempty"`
 }
 
 // Feature holds information about a feature that can be implemented by
@@ -71,13 +90,15 @@
 
 // Text defines a message to be displayed.
 type Text struct {
-	// Msg and Select contains the message to be displayed. Within a Text value
-	// either Msg or Select is defined.
+	// Msg and Select contains the message to be displayed. Msg may be used as
+	// a fallback value if none of the select cases match.
 	Msg    string  `json:"msg,omitempty"`
 	Select *Select `json:"select,omitempty"`
+
 	// Var defines a map of variables that may be substituted in the selected
 	// message.
 	Var map[string]Text `json:"var,omitempty"`
+
 	// Example contains an example message formatted with default values.
 	Example string `json:"example,omitempty"`
 }
@@ -86,6 +107,12 @@
 // a certain argument.
 type Select struct {
 	Feature string          `json:"feature"` // Name of variable or Feature type
-	Arg     interface{}     `json:"arg"`     // The argument ID.
+	Arg     string          `json:"arg"`     // The placeholder ID
 	Cases   map[string]Text `json:"cases"`
 }
+
+// TODO: order matters, but can we derive the ordering from the case keys?
+// type Case struct {
+// 	Key   string `json:"key"`
+// 	Value Text   `json:"value"`
+// }
diff --git a/internal/format/parser.go b/internal/format/parser.go
index 68a8e8e..f4f37f4 100644
--- a/internal/format/parser.go
+++ b/internal/format/parser.go
@@ -28,6 +28,8 @@
 	PlusV  bool
 	SharpV bool
 
+	HasIndex bool
+
 	Width int
 	Prec  int // precision
 
@@ -94,6 +96,8 @@
 
 	p.PlusV = false
 	p.SharpV = false
+
+	p.HasIndex = false
 }
 
 // Scan scans the next part of the format string and sets the status to
@@ -220,6 +224,7 @@
 	if !afterIndex {
 		i, afterIndex = p.updateArgNumber(format, i)
 	}
+	p.HasIndex = afterIndex
 
 	if i >= end {
 		p.endPos = i