diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa1dc93..7d3554a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,8 +10,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 ### Added
 
 - GitHub Actions CI with test, lint (golangci-lint), and vulncheck jobs
+- `TransferBody.TransactionValue` (TAIP-3) — optional fiat-equivalent value
+  (`amount`, `currency`) for Travel Rule threshold determination when an asset
+  is not widely traded
 
 ### Changed
 
-- Bumped Go from 1.25.0 to 1.25.3 to fix stdlib vulnerabilities
+- Bumped Go from 1.25.0 to 1.26.2 to fix stdlib vulnerabilities
 - Use published go-didcomm v0.1.0 instead of local replace directive
+- **BREAKING (TAIP-17):** Renamed `Escrow` message type to `Lock`. Constants,
+  types, constructors, files, and CLI subcommand all renamed:
+  `TypeEscrow` → `TypeLock`, `EscrowBody` → `LockBody`,
+  `NewEscrowMessage` → `NewLockMessage`, `escrow.go` → `lock.go`,
+  `tap message escrow` → `tap message lock`. The `EscrowAgent` role name is
+  preserved.
+- **BREAKING (TAIP-18):** Renamed `Exchange` message type to `RFQ` (Request
+  for Quote). `TypeExchange` → `TypeRFQ`, `ExchangeBody` → `RFQBody`,
+  `NewExchangeMessage` → `NewRFQMessage`, `exchange.go` → `rfq.go`,
+  `tap message exchange` → `tap message rfq`.
diff --git a/CLAUDE.md b/CLAUDE.md
index d8c6750..cf9f64d 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -53,9 +53,9 @@ Single flat `tap` package — all types and helpers in the root. One file per me
 | `client.go` | `Client` wrapping `didcomm.Client`, `Receive()` returning `TAPResult` |
 | `transfer.go` | `TransferBody` + `NewTransferMessage()` |
 | `payment.go` | `PaymentBody` + `NewPaymentMessage()` |
-| `exchange.go` | `ExchangeBody` + `NewExchangeMessage()` |
+| `rfq.go` | `RFQBody` + `NewRFQMessage()` |
 | `quote.go` | `QuoteBody` + `NewQuoteMessage()` |
-| `escrow.go` | `EscrowBody` + `NewEscrowMessage()` |
+| `lock.go` | `LockBody` + `NewLockMessage()` |
 | `authorize.go` | `AuthorizeBody` + `NewAuthorizeMessage()` |
 | `authorization_required.go` | `AuthorizationRequiredBody` + `NewAuthorizationRequiredMessage()` |
 | `settle.go` | `SettleBody` + `NewSettleMessage()` |
diff --git a/README.md b/README.md
index 51943db..0bfc186 100644
--- a/README.md
+++ b/README.md
@@ -159,9 +159,9 @@ envelope, _ := dc.PackAuthcrypt(ctx, authorizeMsg)
 |------------|-------------|------|-----------------|
 | `NewTransferMessage` | `TransferBody` | [TAIP-3](https://tap.rsvp/TAIPs/taip-3) | `asset`, `agents` |
 | `NewPaymentMessage` | `PaymentBody` | [TAIP-14](https://tap.rsvp/TAIPs/taip-14) | `amount`, `merchant`, `agents`, `asset` or `currency` |
-| `NewExchangeMessage` | `ExchangeBody` | [TAIP-18](https://tap.rsvp/TAIPs/taip-18) | `fromAssets`, `toAssets`, `requester`, `agents`, `fromAmount` or `toAmount` |
+| `NewRFQMessage` | `RFQBody` | [TAIP-18](https://tap.rsvp/TAIPs/taip-18) | `fromAssets`, `toAssets`, `requester`, `agents`, `fromAmount` or `toAmount` |
 | `NewQuoteMessage` | `QuoteBody` | [TAIP-18](https://tap.rsvp/TAIPs/taip-18) | `fromAsset`, `toAsset`, `fromAmount`, `toAmount`, `provider`, `agents`, `expiresAt` |
-| `NewEscrowMessage` | `EscrowBody` | [TAIP-17](https://tap.rsvp/TAIPs/taip-17) | `amount`, `originator`, `beneficiary`, `expiry`, `agents`, `asset` or `currency` |
+| `NewLockMessage` | `LockBody` | [TAIP-17](https://tap.rsvp/TAIPs/taip-17) | `amount`, `originator`, `beneficiary`, `expiry`, `agents`, `asset` or `currency` |
 
 ### Authorization Flow Messages
 
@@ -331,7 +331,7 @@ The `receive` command outputs JSON with the unpacked message, typed body, and en
 
 ### TAP message types
 
-**Initiating (no `--thid`):** `transfer`, `payment`, `exchange`, `escrow`, `connect`
+**Initiating (no `--thid`):** `transfer`, `payment`, `rfq`, `lock`, `connect`
 
 **Reply (require `--thid`):** `authorize`, `authorization-required`, `settle`, `reject`, `cancel`, `revert`, `capture`, `quote`, `add-agents`, `remove-agent`, `replace-agent`, `update-agent`, `update-party`, `update-policies`, `confirm-relationship`
 
diff --git a/cmd/tap/main.go b/cmd/tap/main.go
index e843b33..ef88da8 100644
--- a/cmd/tap/main.go
+++ b/cmd/tap/main.go
@@ -28,7 +28,7 @@ Commands:
   help                                                      Print this help
 
 TAP message types:
-  Initiating:  transfer, payment, exchange, escrow, connect
+  Initiating:  transfer, payment, rfq, lock, connect
   Reply:       authorize, authorization-required, settle, reject, cancel,
                revert, capture, quote, add-agents, remove-agent,
                replace-agent, update-agent, update-party, update-policies,
diff --git a/cmd/tap/message.go b/cmd/tap/message.go
index 4462e5e..2f2772f 100644
--- a/cmd/tap/message.go
+++ b/cmd/tap/message.go
@@ -16,7 +16,7 @@ import (
 const messageUsage = `Usage: tap message <type> --from <did> --to <did> [--thid <id>] [--body <json>]
 
 Initiating types (no --thid):
-  transfer, payment, exchange, escrow, connect
+  transfer, payment, rfq, lock, connect
 
 Reply types (require --thid):
   authorize, authorization-required, settle, reject, cancel, revert,
@@ -111,10 +111,10 @@ func runMessage(args []string) error {
 		return runMessageTransfer(msgArgs)
 	case "payment":
 		return runMessagePayment(msgArgs)
-	case "exchange":
-		return runMessageExchange(msgArgs)
-	case "escrow":
-		return runMessageEscrow(msgArgs)
+	case "rfq":
+		return runMessageRFQ(msgArgs)
+	case "lock":
+		return runMessageLock(msgArgs)
 	case "connect":
 		return runMessageConnect(msgArgs)
 
@@ -189,32 +189,32 @@ func runMessagePayment(args []string) error {
 	return writeMessage(msg)
 }
 
-func runMessageExchange(args []string) error {
-	f, err := parseMessageFlags("exchange", args, false)
+func runMessageRFQ(args []string) error {
+	f, err := parseMessageFlags("rfq", args, false)
 	if err != nil {
 		return err
 	}
-	var body tap.ExchangeBody
+	var body tap.RFQBody
 	if err := json.Unmarshal(f.body, &body); err != nil {
 		return fmt.Errorf("parse body JSON: %w", err)
 	}
-	msg, err := tap.NewExchangeMessage(f.from, f.to, &body)
+	msg, err := tap.NewRFQMessage(f.from, f.to, &body)
 	if err != nil {
 		return err
 	}
 	return writeMessage(msg)
 }
 
-func runMessageEscrow(args []string) error {
-	f, err := parseMessageFlags("escrow", args, false)
+func runMessageLock(args []string) error {
+	f, err := parseMessageFlags("lock", args, false)
 	if err != nil {
 		return err
 	}
-	var body tap.EscrowBody
+	var body tap.LockBody
 	if err := json.Unmarshal(f.body, &body); err != nil {
 		return fmt.Errorf("parse body JSON: %w", err)
 	}
-	msg, err := tap.NewEscrowMessage(f.from, f.to, &body)
+	msg, err := tap.NewLockMessage(f.from, f.to, &body)
 	if err != nil {
 		return err
 	}
diff --git a/cmd/tap/message_test.go b/cmd/tap/message_test.go
index 57920d6..7534f5e 100644
--- a/cmd/tap/message_test.go
+++ b/cmd/tap/message_test.go
@@ -237,49 +237,49 @@ func TestCLI_MessagePayment(t *testing.T) {
 	}
 }
 
-func TestCLI_MessageExchange(t *testing.T) {
+func TestCLI_MessageRFQ(t *testing.T) {
 	bin := buildBinary(t)
 	body := `{"fromAssets":["eip155:1/slip44:60"],"toAssets":["eip155:1/slip44:0"],"fromAmount":"1.0","requester":{"@id":"did:key:z1"},"agents":[{"@id":"did:key:z1","role":"OriginatingVASP"}]}`
 
-	cmd := exec.Command(bin, "message", "exchange",
+	cmd := exec.Command(bin, "message", "rfq",
 		"--from", "did:key:z1",
 		"--to", "did:key:z2",
 		"--body", body,
 	)
 	out, err := cmd.Output()
 	if err != nil {
-		t.Fatalf("message exchange failed: %s", err)
+		t.Fatalf("message rfq failed: %s", err)
 	}
 
 	var msg didcomm.Message
 	if err := json.Unmarshal(out, &msg); err != nil {
 		t.Fatalf("invalid JSON: %s", err)
 	}
-	if msg.Type != tap.TypeExchange {
-		t.Fatalf("expected type %s, got %s", tap.TypeExchange, msg.Type)
+	if msg.Type != tap.TypeRFQ {
+		t.Fatalf("expected type %s, got %s", tap.TypeRFQ, msg.Type)
 	}
 }
 
-func TestCLI_MessageEscrow(t *testing.T) {
+func TestCLI_MessageLock(t *testing.T) {
 	bin := buildBinary(t)
 	body := `{"asset":"eip155:1/slip44:60","amount":"5.0","originator":{"@id":"did:key:z1"},"beneficiary":{"@id":"did:key:z2"},"expiry":"2025-12-31T23:59:59Z","agents":[{"@id":"did:key:z1","role":"OriginatingVASP"}]}`
 
-	cmd := exec.Command(bin, "message", "escrow",
+	cmd := exec.Command(bin, "message", "lock",
 		"--from", "did:key:z1",
 		"--to", "did:key:z2",
 		"--body", body,
 	)
 	out, err := cmd.Output()
 	if err != nil {
-		t.Fatalf("message escrow failed: %s", err)
+		t.Fatalf("message lock failed: %s", err)
 	}
 
 	var msg didcomm.Message
 	if err := json.Unmarshal(out, &msg); err != nil {
 		t.Fatalf("invalid JSON: %s", err)
 	}
-	if msg.Type != tap.TypeEscrow {
-		t.Fatalf("expected type %s, got %s", tap.TypeEscrow, msg.Type)
+	if msg.Type != tap.TypeLock {
+		t.Fatalf("expected type %s, got %s", tap.TypeLock, msg.Type)
 	}
 }
 
diff --git a/doc.go b/doc.go
index 13fc4e1..38ce3dd 100644
--- a/doc.go
+++ b/doc.go
@@ -16,9 +16,9 @@
 // Transaction messages initiate financial operations:
 //   - Transfer (TAIP-3) — asset transfer between parties
 //   - Payment (TAIP-14) — merchant payment request
-//   - Exchange (TAIP-18) — asset exchange request
+//   - RFQ (TAIP-18) — request for quote on an asset exchange
 //   - Quote (TAIP-18) — exchange price quote response
-//   - Escrow (TAIP-17) — hold funds in escrow
+//   - Lock (TAIP-17) — hold funds in escrow
 //
 // Authorization flow messages manage transaction lifecycle:
 //   - Authorize (TAIP-4) — approve a transaction
@@ -27,7 +27,7 @@
 //   - Reject (TAIP-4) — reject a transaction
 //   - Cancel (TAIP-4) — cancel a transaction
 //   - Revert (TAIP-4) — request reversal of settled transaction
-//   - Capture (TAIP-17) — release escrowed funds
+//   - Capture (TAIP-17) — release locked funds
 //
 // Agent management messages modify transaction participants:
 //   - UpdateAgent (TAIP-5) — update agent information
diff --git a/go.mod b/go.mod
index 3f78d6b..63fcb81 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/TransactionAuthorizationProtocol/tap-go
 
-go 1.26.0
+go 1.26.2
 
 require (
 	github.com/Notabene-id/go-didcomm v0.2.0
diff --git a/escrow.go b/lock.go
similarity index 79%
rename from escrow.go
rename to lock.go
index 18d6fa3..a712881 100644
--- a/escrow.go
+++ b/lock.go
@@ -8,8 +8,8 @@ import (
 	"github.com/google/uuid"
 )
 
-// EscrowBody represents the body of a TAP Escrow message (TAIP-17).
-type EscrowBody struct {
+// LockBody represents the body of a TAP Lock message (TAIP-17).
+type LockBody struct {
 	Context     string  `json:"@context"`
 	Type        string  `json:"@type"`
 	Asset       string  `json:"asset,omitempty"`
@@ -22,10 +22,10 @@ type EscrowBody struct {
 	Agreement   string  `json:"agreement,omitempty"`
 }
 
-func (b *EscrowBody) TAPType() string { return TypeEscrow }
+func (b *LockBody) TAPType() string { return TypeLock }
 
-// NewEscrowMessage creates a new DIDComm message with an Escrow body.
-func NewEscrowMessage(from string, to []string, body *EscrowBody) (*didcomm.Message, error) {
+// NewLockMessage creates a new DIDComm message with a Lock body.
+func NewLockMessage(from string, to []string, body *LockBody) (*didcomm.Message, error) {
 	if body.Amount == "" {
 		return nil, fmt.Errorf("%w: missing amount", ErrInvalidBody)
 	}
@@ -46,7 +46,7 @@ func NewEscrowMessage(from string, to []string, body *EscrowBody) (*didcomm.Mess
 	}
 
 	body.Context = TAPContext
-	body.Type = TypeEscrow
+	body.Type = TypeLock
 
 	rawBody, err := json.Marshal(body)
 	if err != nil {
@@ -55,7 +55,7 @@ func NewEscrowMessage(from string, to []string, body *EscrowBody) (*didcomm.Mess
 
 	return &didcomm.Message{
 		ID:   uuid.New().String(),
-		Type: TypeEscrow,
+		Type: TypeLock,
 		From: from,
 		To:   to,
 		Body: rawBody,
diff --git a/escrow_test.go b/lock_test.go
similarity index 67%
rename from escrow_test.go
rename to lock_test.go
index 52a9594..0a5b1c0 100644
--- a/escrow_test.go
+++ b/lock_test.go
@@ -7,8 +7,8 @@ import (
 	"testing"
 )
 
-func TestNewEscrowMessage(t *testing.T) {
-	body := &EscrowBody{
+func TestNewLockMessage(t *testing.T) {
+	body := &LockBody{
 		Asset:       "eip155:1/erc20:0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
 		Amount:      "1000.00",
 		Originator:  &Party{ID: "did:web:buyer.example"},
@@ -19,17 +19,17 @@ func TestNewEscrowMessage(t *testing.T) {
 		},
 	}
 
-	msg, err := NewEscrowMessage("did:web:buyer.example", []string{"did:web:escrow-service.example"}, body)
+	msg, err := NewLockMessage("did:web:buyer.example", []string{"did:web:escrow-service.example"}, body)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if msg.Type != TypeEscrow {
+	if msg.Type != TypeLock {
 		t.Errorf("Type: got %q", msg.Type)
 	}
 }
 
-func TestNewEscrowMessage_MissingFields(t *testing.T) {
-	base := EscrowBody{
+func TestNewLockMessage_MissingFields(t *testing.T) {
+	base := LockBody{
 		Asset:       "eip155:1/erc20:0xA0b86991",
 		Amount:      "1000.00",
 		Originator:  &Party{ID: "did:web:buyer"},
@@ -40,21 +40,21 @@ func TestNewEscrowMessage_MissingFields(t *testing.T) {
 
 	tests := []struct {
 		name   string
-		modify func(*EscrowBody)
+		modify func(*LockBody)
 	}{
-		{"missing amount", func(b *EscrowBody) { b.Amount = "" }},
-		{"missing originator", func(b *EscrowBody) { b.Originator = nil }},
-		{"missing beneficiary", func(b *EscrowBody) { b.Beneficiary = nil }},
-		{"missing expiry", func(b *EscrowBody) { b.Expiry = "" }},
-		{"missing agents", func(b *EscrowBody) { b.Agents = nil }},
-		{"missing asset and currency", func(b *EscrowBody) { b.Asset = "" }},
+		{"missing amount", func(b *LockBody) { b.Amount = "" }},
+		{"missing originator", func(b *LockBody) { b.Originator = nil }},
+		{"missing beneficiary", func(b *LockBody) { b.Beneficiary = nil }},
+		{"missing expiry", func(b *LockBody) { b.Expiry = "" }},
+		{"missing agents", func(b *LockBody) { b.Agents = nil }},
+		{"missing asset and currency", func(b *LockBody) { b.Asset = "" }},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			b := base
 			tt.modify(&b)
-			_, err := NewEscrowMessage("from", nil, &b)
+			_, err := NewLockMessage("from", nil, &b)
 			if !errors.Is(err, ErrInvalidBody) {
 				t.Errorf("expected ErrInvalidBody, got %v", err)
 			}
@@ -62,10 +62,10 @@ func TestNewEscrowMessage_MissingFields(t *testing.T) {
 	}
 }
 
-func TestEscrowBody_JSONRoundTrip(t *testing.T) {
-	body := EscrowBody{
+func TestLockBody_JSONRoundTrip(t *testing.T) {
+	body := LockBody{
 		Context:     TAPContext,
-		Type:        TypeEscrow,
+		Type:        TypeLock,
 		Asset:       "eip155:1/erc20:0xa0b86991",
 		Amount:      "1000.00",
 		Originator:  &Party{ID: "did:web:buyer.example"},
@@ -79,7 +79,7 @@ func TestEscrowBody_JSONRoundTrip(t *testing.T) {
 		t.Fatalf("marshal: %v", err)
 	}
 
-	var got EscrowBody
+	var got LockBody
 	if err := json.Unmarshal(data, &got); err != nil {
 		t.Fatalf("unmarshal: %v", err)
 	}
@@ -88,8 +88,8 @@ func TestEscrowBody_JSONRoundTrip(t *testing.T) {
 	}
 }
 
-func TestEscrow_TestVectorValid(t *testing.T) {
-	data, err := os.ReadFile("TAIPs/test-vectors/escrow/valid-escrow.json")
+func TestLock_TestVectorValid(t *testing.T) {
+	data, err := os.ReadFile("TAIPs/test-vectors/lock/valid-lock.json")
 	if err != nil {
 		t.Skipf("test vector not available: %v", err)
 	}
@@ -103,7 +103,7 @@ func TestEscrow_TestVectorValid(t *testing.T) {
 		t.Fatalf("unmarshal test vector: %v", err)
 	}
 
-	var body EscrowBody
+	var body LockBody
 	if err := json.Unmarshal(tv.Message.Body, &body); err != nil {
 		t.Fatalf("unmarshal body: %v", err)
 	}
@@ -119,8 +119,8 @@ func TestEscrow_TestVectorValid(t *testing.T) {
 	}
 }
 
-func TestEscrowBody_ParseBody(t *testing.T) {
-	body := &EscrowBody{
+func TestLockBody_ParseBody(t *testing.T) {
+	body := &LockBody{
 		Asset:       "eip155:1/erc20:0xa0b86991",
 		Amount:      "500.00",
 		Originator:  &Party{ID: "did:web:buyer"},
@@ -128,7 +128,7 @@ func TestEscrowBody_ParseBody(t *testing.T) {
 		Expiry:      "2024-12-31T00:00:00Z",
 		Agents:      []Agent{{ID: "did:web:escrow", Role: "EscrowAgent"}},
 	}
-	msg, err := NewEscrowMessage("did:web:buyer", []string{"did:web:escrow"}, body)
+	msg, err := NewLockMessage("did:web:buyer", []string{"did:web:escrow"}, body)
 	if err != nil {
 		t.Fatalf("create: %v", err)
 	}
@@ -137,11 +137,11 @@ func TestEscrowBody_ParseBody(t *testing.T) {
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
-	eb, ok := parsed.(*EscrowBody)
+	lb, ok := parsed.(*LockBody)
 	if !ok {
-		t.Fatalf("expected *EscrowBody, got %T", parsed)
+		t.Fatalf("expected *LockBody, got %T", parsed)
 	}
-	if eb.Amount != "500.00" {
-		t.Errorf("Amount: got %q", eb.Amount)
+	if lb.Amount != "500.00" {
+		t.Errorf("Amount: got %q", lb.Amount)
 	}
 }
diff --git a/message_types.go b/message_types.go
index be3f525..c0211bf 100644
--- a/message_types.go
+++ b/message_types.go
@@ -7,9 +7,9 @@ const (
 	// Transaction message types
 	TypeTransfer = "https://tap.rsvp/schema/1.0#Transfer"
 	TypePayment  = "https://tap.rsvp/schema/1.0#Payment"
-	TypeExchange = "https://tap.rsvp/schema/1.0#Exchange"
+	TypeRFQ      = "https://tap.rsvp/schema/1.0#RFQ"
 	TypeQuote    = "https://tap.rsvp/schema/1.0#Quote"
-	TypeEscrow   = "https://tap.rsvp/schema/1.0#Escrow"
+	TypeLock     = "https://tap.rsvp/schema/1.0#Lock"
 
 	// Authorization flow message types
 	TypeAuthorize             = "https://tap.rsvp/schema/1.0#Authorize"
@@ -38,9 +38,9 @@ func AllTypes() []string {
 	return []string{
 		TypeTransfer,
 		TypePayment,
-		TypeExchange,
+		TypeRFQ,
 		TypeQuote,
-		TypeEscrow,
+		TypeLock,
 		TypeAuthorize,
 		TypeAuthorizationRequired,
 		TypeSettle,
diff --git a/message_types_test.go b/message_types_test.go
index 9c57cff..bb4c9a5 100644
--- a/message_types_test.go
+++ b/message_types_test.go
@@ -9,9 +9,9 @@ func TestTypeConstants(t *testing.T) {
 	types := map[string]string{
 		"Transfer":              TypeTransfer,
 		"Payment":               TypePayment,
-		"Exchange":              TypeExchange,
+		"RFQ":                   TypeRFQ,
 		"Quote":                 TypeQuote,
-		"Escrow":                TypeEscrow,
+		"Lock":                  TypeLock,
 		"Authorize":             TypeAuthorize,
 		"AuthorizationRequired": TypeAuthorizationRequired,
 		"Settle":                TypeSettle,
diff --git a/parse.go b/parse.go
index bdc1862..9d9d129 100644
--- a/parse.go
+++ b/parse.go
@@ -32,12 +32,12 @@ func ParseBody(msg *didcomm.Message) (TAPBody, error) {
 		body = &TransferBody{}
 	case TypePayment:
 		body = &PaymentBody{}
-	case TypeExchange:
-		body = &ExchangeBody{}
+	case TypeRFQ:
+		body = &RFQBody{}
 	case TypeQuote:
 		body = &QuoteBody{}
-	case TypeEscrow:
-		body = &EscrowBody{}
+	case TypeLock:
+		body = &LockBody{}
 	case TypeAuthorize:
 		body = &AuthorizeBody{}
 	case TypeAuthorizationRequired:
diff --git a/parse_test.go b/parse_test.go
index fb2d255..358ff85 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -15,9 +15,9 @@ func TestIsTAPMessage(t *testing.T) {
 	}{
 		{TypeTransfer, true},
 		{TypePayment, true},
-		{TypeExchange, true},
+		{TypeRFQ, true},
 		{TypeQuote, true},
-		{TypeEscrow, true},
+		{TypeLock, true},
 		{TypeAuthorize, true},
 		{TypeAuthorizationRequired, true},
 		{TypeSettle, true},
@@ -53,9 +53,9 @@ func TestParseBody_AllTypes(t *testing.T) {
 	}{
 		{"Transfer", TypeTransfer, &TransferBody{Context: TAPContext, Type: TypeTransfer, Asset: "ETH", Agents: []Agent{{ID: "a"}}}},
 		{"Payment", TypePayment, &PaymentBody{Context: TAPContext, Type: TypePayment, Amount: "100", Currency: "USD", Merchant: &Party{ID: "m"}, Agents: []Agent{{ID: "a"}}}},
-		{"Exchange", TypeExchange, &ExchangeBody{Context: TAPContext, Type: TypeExchange, FromAssets: []string{"ETH"}, ToAssets: []string{"USD"}, FromAmount: "1", Requester: &Party{ID: "r"}, Agents: []Agent{{ID: "a"}}}},
+		{"RFQ", TypeRFQ, &RFQBody{Context: TAPContext, Type: TypeRFQ, FromAssets: []string{"ETH"}, ToAssets: []string{"USD"}, FromAmount: "1", Requester: &Party{ID: "r"}, Agents: []Agent{{ID: "a"}}}},
 		{"Quote", TypeQuote, &QuoteBody{Context: TAPContext, Type: TypeQuote, FromAsset: "ETH", ToAsset: "USD", FromAmount: "1", ToAmount: "3000", Provider: &Party{ID: "p"}, Agents: []Agent{{ID: "a"}}, ExpiresAt: "2025-01-01T00:00:00Z"}},
-		{"Escrow", TypeEscrow, &EscrowBody{Context: TAPContext, Type: TypeEscrow, Asset: "ETH", Amount: "100", Originator: &Party{ID: "o"}, Beneficiary: &Party{ID: "b"}, Expiry: "2025-01-01T00:00:00Z", Agents: []Agent{{ID: "a"}}}},
+		{"Lock", TypeLock, &LockBody{Context: TAPContext, Type: TypeLock, Asset: "ETH", Amount: "100", Originator: &Party{ID: "o"}, Beneficiary: &Party{ID: "b"}, Expiry: "2025-01-01T00:00:00Z", Agents: []Agent{{ID: "a"}}}},
 		{"Authorize", TypeAuthorize, &AuthorizeBody{Context: TAPContext, Type: TypeAuthorize}},
 		{"AuthorizationRequired", TypeAuthorizationRequired, &AuthorizationRequiredBody{Context: TAPContext, Type: TypeAuthorizationRequired, AuthorizationURL: "https://example.com", Expires: "2025-01-01T00:00:00Z"}},
 		{"Settle", TypeSettle, &SettleBody{Context: TAPContext, Type: TypeSettle, SettlementAddress: "eip155:1:0x1234"}},
diff --git a/exchange.go b/rfq.go
similarity index 77%
rename from exchange.go
rename to rfq.go
index 4ce75ed..ec3a0c7 100644
--- a/exchange.go
+++ b/rfq.go
@@ -8,8 +8,8 @@ import (
 	"github.com/google/uuid"
 )
 
-// ExchangeBody represents the body of a TAP Exchange message (TAIP-18).
-type ExchangeBody struct {
+// RFQBody represents the body of a TAP RFQ (Request for Quote) message (TAIP-18).
+type RFQBody struct {
 	Context    string   `json:"@context"`
 	Type       string   `json:"@type"`
 	FromAssets []string `json:"fromAssets"`
@@ -22,10 +22,10 @@ type ExchangeBody struct {
 	Policies   []Policy `json:"policies,omitempty"`
 }
 
-func (b *ExchangeBody) TAPType() string { return TypeExchange }
+func (b *RFQBody) TAPType() string { return TypeRFQ }
 
-// NewExchangeMessage creates a new DIDComm message with an Exchange body.
-func NewExchangeMessage(from string, to []string, body *ExchangeBody) (*didcomm.Message, error) {
+// NewRFQMessage creates a new DIDComm message with an RFQ body.
+func NewRFQMessage(from string, to []string, body *RFQBody) (*didcomm.Message, error) {
 	if len(body.FromAssets) == 0 {
 		return nil, fmt.Errorf("%w: missing fromAssets", ErrInvalidBody)
 	}
@@ -43,7 +43,7 @@ func NewExchangeMessage(from string, to []string, body *ExchangeBody) (*didcomm.
 	}
 
 	body.Context = TAPContext
-	body.Type = TypeExchange
+	body.Type = TypeRFQ
 
 	rawBody, err := json.Marshal(body)
 	if err != nil {
@@ -52,7 +52,7 @@ func NewExchangeMessage(from string, to []string, body *ExchangeBody) (*didcomm.
 
 	return &didcomm.Message{
 		ID:   uuid.New().String(),
-		Type: TypeExchange,
+		Type: TypeRFQ,
 		From: from,
 		To:   to,
 		Body: rawBody,
diff --git a/exchange_test.go b/rfq_test.go
similarity index 67%
rename from exchange_test.go
rename to rfq_test.go
index ee7c1ed..0aeb9af 100644
--- a/exchange_test.go
+++ b/rfq_test.go
@@ -6,8 +6,8 @@ import (
 	"testing"
 )
 
-func TestNewExchangeMessage(t *testing.T) {
-	body := &ExchangeBody{
+func TestNewRFQMessage(t *testing.T) {
+	body := &RFQBody{
 		FromAssets: []string{"eip155:1/slip44:60"},
 		ToAssets:   []string{"USD"},
 		FromAmount: "1.0",
@@ -15,15 +15,15 @@ func TestNewExchangeMessage(t *testing.T) {
 		Agents:     []Agent{{ID: "did:web:exchange.example", For: NewForField("did:eg:alice")}},
 	}
 
-	msg, err := NewExchangeMessage("did:web:exchange.example", []string{"did:web:provider.example"}, body)
+	msg, err := NewRFQMessage("did:web:exchange.example", []string{"did:web:provider.example"}, body)
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
-	if msg.Type != TypeExchange {
+	if msg.Type != TypeRFQ {
 		t.Errorf("Type: got %q", msg.Type)
 	}
 
-	var got ExchangeBody
+	var got RFQBody
 	if err := json.Unmarshal(msg.Body, &got); err != nil {
 		t.Fatalf("unmarshal: %v", err)
 	}
@@ -32,36 +32,36 @@ func TestNewExchangeMessage(t *testing.T) {
 	}
 }
 
-func TestNewExchangeMessage_MissingFromAssets(t *testing.T) {
-	body := &ExchangeBody{
+func TestNewRFQMessage_MissingFromAssets(t *testing.T) {
+	body := &RFQBody{
 		ToAssets:   []string{"USD"},
 		FromAmount: "1.0",
 		Requester:  &Party{ID: "did:eg:alice"},
 		Agents:     []Agent{{ID: "did:web:exchange.example"}},
 	}
-	_, err := NewExchangeMessage("from", nil, body)
+	_, err := NewRFQMessage("from", nil, body)
 	if !errors.Is(err, ErrInvalidBody) {
 		t.Errorf("expected ErrInvalidBody, got %v", err)
 	}
 }
 
-func TestNewExchangeMessage_MissingAmounts(t *testing.T) {
-	body := &ExchangeBody{
+func TestNewRFQMessage_MissingAmounts(t *testing.T) {
+	body := &RFQBody{
 		FromAssets: []string{"ETH"},
 		ToAssets:   []string{"USD"},
 		Requester:  &Party{ID: "did:eg:alice"},
 		Agents:     []Agent{{ID: "did:web:exchange.example"}},
 	}
-	_, err := NewExchangeMessage("from", nil, body)
+	_, err := NewRFQMessage("from", nil, body)
 	if !errors.Is(err, ErrInvalidBody) {
 		t.Errorf("expected ErrInvalidBody, got %v", err)
 	}
 }
 
-func TestExchangeBody_JSONRoundTrip(t *testing.T) {
-	body := ExchangeBody{
+func TestRFQBody_JSONRoundTrip(t *testing.T) {
+	body := RFQBody{
 		Context:    TAPContext,
-		Type:       TypeExchange,
+		Type:       TypeRFQ,
 		FromAssets: []string{"eip155:1/slip44:60"},
 		ToAssets:   []string{"USD"},
 		FromAmount: "1.0",
@@ -74,7 +74,7 @@ func TestExchangeBody_JSONRoundTrip(t *testing.T) {
 		t.Fatalf("marshal: %v", err)
 	}
 
-	var got ExchangeBody
+	var got RFQBody
 	if err := json.Unmarshal(data, &got); err != nil {
 		t.Fatalf("unmarshal: %v", err)
 	}
@@ -83,15 +83,15 @@ func TestExchangeBody_JSONRoundTrip(t *testing.T) {
 	}
 }
 
-func TestExchangeBody_ParseBody(t *testing.T) {
-	body := &ExchangeBody{
+func TestRFQBody_ParseBody(t *testing.T) {
+	body := &RFQBody{
 		FromAssets: []string{"ETH"},
 		ToAssets:   []string{"USD"},
 		ToAmount:   "3000.00",
 		Requester:  &Party{ID: "did:eg:alice"},
 		Agents:     []Agent{{ID: "did:web:exchange.example"}},
 	}
-	msg, err := NewExchangeMessage("did:web:exchange.example", nil, body)
+	msg, err := NewRFQMessage("did:web:exchange.example", nil, body)
 	if err != nil {
 		t.Fatalf("create: %v", err)
 	}
@@ -100,11 +100,11 @@ func TestExchangeBody_ParseBody(t *testing.T) {
 	if err != nil {
 		t.Fatalf("parse: %v", err)
 	}
-	eb, ok := parsed.(*ExchangeBody)
+	rb, ok := parsed.(*RFQBody)
 	if !ok {
-		t.Fatalf("expected *ExchangeBody, got %T", parsed)
+		t.Fatalf("expected *RFQBody, got %T", parsed)
 	}
-	if eb.ToAmount != "3000.00" {
-		t.Errorf("ToAmount: got %q", eb.ToAmount)
+	if rb.ToAmount != "3000.00" {
+		t.Errorf("ToAmount: got %q", rb.ToAmount)
 	}
 }
diff --git a/transfer.go b/transfer.go
index 4557611..1da8f0b 100644
--- a/transfer.go
+++ b/transfer.go
@@ -10,16 +10,26 @@ import (
 
 // TransferBody represents the body of a TAP Transfer message (TAIP-3).
 type TransferBody struct {
-	Context      string  `json:"@context"`
-	Type         string  `json:"@type"`
-	Asset        string  `json:"asset"`
-	Amount       string  `json:"amount,omitempty"`
-	Originator   *Party  `json:"originator,omitempty"`
-	Beneficiary  *Party  `json:"beneficiary,omitempty"`
-	Agents       []Agent `json:"agents"`
-	SettlementID string  `json:"settlementId,omitempty"`
-	Memo         string  `json:"memo,omitempty"`
-	Expiry       string  `json:"expiry,omitempty"`
+	Context          string            `json:"@context"`
+	Type             string            `json:"@type"`
+	Asset            string            `json:"asset"`
+	Amount           string            `json:"amount,omitempty"`
+	Originator       *Party            `json:"originator,omitempty"`
+	Beneficiary      *Party            `json:"beneficiary,omitempty"`
+	Agents           []Agent           `json:"agents"`
+	SettlementID     string            `json:"settlementId,omitempty"`
+	Memo             string            `json:"memo,omitempty"`
+	Expiry           string            `json:"expiry,omitempty"`
+	TransactionValue *TransactionValue `json:"transactionValue,omitempty"`
+}
+
+// TransactionValue represents the fiat equivalent value of a transfer for compliance
+// purposes such as Travel Rule threshold determination (TAIP-3).
+type TransactionValue struct {
+	// Amount is the decimal string representation of the fiat amount.
+	Amount string `json:"amount"`
+	// Currency is the ISO 4217 3-letter currency code (e.g. "USD", "EUR").
+	Currency string `json:"currency"`
 }
 
 func (b *TransferBody) TAPType() string { return TypeTransfer }
diff --git a/transfer_test.go b/transfer_test.go
index fab1c16..d4b9ef8 100644
--- a/transfer_test.go
+++ b/transfer_test.go
@@ -123,6 +123,60 @@ func TestTransferBody_ParseBody(t *testing.T) {
 	}
 }
 
+func TestTransferBody_TransactionValue(t *testing.T) {
+	body := &TransferBody{
+		Asset:  "eip155:1/erc20:0x1234567890abcdef1234567890abcdef12345678",
+		Amount: "500",
+		TransactionValue: &TransactionValue{
+			Amount:   "1250.00",
+			Currency: "EUR",
+		},
+		Agents: []Agent{{ID: "did:web:originator.vasp", For: NewForField("did:eg:bob")}},
+	}
+
+	msg, err := NewTransferMessage("did:web:originator.vasp", []string{"did:web:beneficiary.vasp"}, body)
+	if err != nil {
+		t.Fatalf("create: %v", err)
+	}
+
+	parsed, err := ParseBody(msg)
+	if err != nil {
+		t.Fatalf("parse: %v", err)
+	}
+	tb := parsed.(*TransferBody)
+	if tb.TransactionValue == nil {
+		t.Fatal("TransactionValue: got nil")
+	}
+	if tb.TransactionValue.Amount != "1250.00" {
+		t.Errorf("TransactionValue.Amount: got %q", tb.TransactionValue.Amount)
+	}
+	if tb.TransactionValue.Currency != "EUR" {
+		t.Errorf("TransactionValue.Currency: got %q", tb.TransactionValue.Currency)
+	}
+
+	// transactionValue is optional — confirm omitempty when nil
+	bodyNoValue := &TransferBody{
+		Asset:  "eip155:1/slip44:60",
+		Agents: []Agent{{ID: "did:web:originator.vasp"}},
+	}
+	msg2, err := NewTransferMessage("did:web:originator.vasp", nil, bodyNoValue)
+	if err != nil {
+		t.Fatalf("create: %v", err)
+	}
+	if string(msg2.Body) == "" || jsonContains(msg2.Body, "transactionValue") {
+		t.Errorf("expected no transactionValue field, body=%s", msg2.Body)
+	}
+}
+
+func jsonContains(body []byte, key string) bool {
+	for i := 0; i < len(body)-len(key); i++ {
+		if string(body[i:i+len(key)]) == key {
+			return true
+		}
+	}
+	return false
+}
+
 func TestTransfer_TestVectorValid(t *testing.T) {
 	data, err := os.ReadFile("TAIPs/test-vectors/transfer/valid.json")
 	if err != nil {