diff --git a/README.md b/README.md
index c9ed066..97d8223 100644
--- a/README.md
+++ b/README.md
@@ -36,15 +36,19 @@ if err != nil {
 }
 ```
 
-Use `GetSegmentType(segment string)` to read the segment type from a segment value:
-- `0` = *Core String*
-- `1` = *Disclosed Vendors*
-- `2` = *Allowed Vendors*
-- `3` = *Publisher TC*
+Use `GetSegmentType(segment string) (segmentType SegmentType, err error)` to read the segment type from a segment value:
+- `SegmentTypeUndefined` = undefined
+- `SegmentTypeCoreString` = *Core String*
+- `SegmentTypeDisclosedVendors` = *Disclosed Vendors*
+- `SegmentTypeAllowedVendors` = *Allowed Vendors*
+- `SegmentTypePublisherTC` = *Publisher TC*
 
-Use `GetVersion(s string)` to verify the cookie version from a TC String or a *Core String* segment value. This function also supports TCF V1.1 consent strings:
-- `1` = TCF V1.1
-- `2` = TCF V2.0
+You can find more information about segment types [here](https://github.com/InteractiveAdvertisingBureau/GDPR-Transparency-and-Consent-Framework/blob/master/TCFv2/IAB%20Tech%20Lab%20-%20Consent%20string%20and%20vendor%20list%20formats%20v2.md#disclosed-vendors-oob).
+
+Use `GetVersion(s string) (version TcfVersion, err error)` to read the cookie version from a TC String or a *Core String* segment value. This function also supports TCF V1.1 consent strings:
+- `TcfVersionUndefined` = undefined
+- `TcfVersion1` = TCF V1.1
+- `TcfVersion2` = TCF V2.0
 
 #### Example
 ```
diff --git a/constants.go b/constants.go
new file mode 100644
index 0000000..a8377d6
--- /dev/null
+++ b/constants.go
@@ -0,0 +1,19 @@
+package iabtcfv2
+
+type SegmentType int
+
+const (
+	SegmentTypeUndefined        SegmentType = -1
+	SegmentTypeCoreString       SegmentType = 0
+	SegmentTypeDisclosedVendors SegmentType = 1
+	SegmentTypeAllowedVendors   SegmentType = 2
+	SegmentTypePublisherTC      SegmentType = 3
+)
+
+type TcfVersion int
+
+const (
+	TcfVersionUndefined TcfVersion = -1
+	TcfVersion1         TcfVersion = 1
+	TcfVersion2         TcfVersion = 2
+)
diff --git a/decode.go b/decode.go
index b7f3417..1f6e456 100644
--- a/decode.go
+++ b/decode.go
@@ -6,9 +6,12 @@ import (
 	"strings"
 )
 
-// Decodes a string and returns the TCF version
+// Decodes a string and returns the TcfVersion
 // It can also decode version from a TCF V1.1 consent string
-func GetVersion(s string) (version int, err error) {
+// - TcfVersionUndefined = -1
+// - TcfVersion1 = 1
+// - TcfVersion2 = 2
+func GetVersion(s string) (version TcfVersion, err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			err = fmt.Errorf("%v", r)
@@ -17,19 +20,20 @@ func GetVersion(s string) (version int, err error) {
 
 	b, err := base64.RawURLEncoding.DecodeString(s)
 	if err != nil {
-		return 0, err
+		return TcfVersionUndefined, err
 	}
 
 	var e = newTCEncoder(b)
-	return e.readInt(6), nil
+	return TcfVersion(e.readInt(6)), nil
 }
 
-// Decodes a segment value and returns the type
-// - 0 = Core String
-// - 1 = Disclosed Vendors
-// - 2 = Allowed Vendors
-// - 3 = Publisher TC
-func GetSegmentType(segment string) (segmentType int, err error) {
+// Decodes a segment value and returns the SegmentType
+// - SegmentTypeUndefined = -1
+// - SegmentTypeCoreString = 0
+// - SegmentTypeDisclosedVendors = 1
+// - SegmentTypeAllowedVendors = 2
+// - SegmentTypePublisherTC = 3
+func GetSegmentType(segment string) (segmentType SegmentType, err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			err = fmt.Errorf("%v", r)
@@ -38,11 +42,11 @@ func GetSegmentType(segment string) (segmentType int, err error) {
 
 	b, err := base64.RawURLEncoding.DecodeString(segment)
 	if err != nil {
-		return 0, err
+		return SegmentTypeUndefined, err
 	}
 
 	var e = newTCEncoder(b)
-	return e.readInt(3), nil
+	return SegmentType(e.readInt(3)), nil
 }
 
 // Decode a TC String and returns it as a TCData structure
@@ -53,55 +57,55 @@ func GetSegmentType(segment string) (segmentType int, err error) {
 // - Publisher TC
 func Decode(tcString string) (t *TCData, err error) {
 	t = &TCData{}
-	mapSegments := map[int]bool{}
+	mapSegments := map[SegmentType]bool{}
 	for i, v := range strings.Split(tcString, ".") {
 		segmentType, err := GetSegmentType(v)
 		if err != nil {
 			return nil, err
 		}
 
-		if segmentType == disclosedVendorsType {
-			if mapSegments[disclosedVendorsType] == true {
+		if segmentType == SegmentTypeDisclosedVendors {
+			if mapSegments[SegmentTypeDisclosedVendors] == true {
 				return nil, fmt.Errorf("duplicate Disclosed Vendors segment")
 			}
 			segment, err := DecodeDisclosedVendors(v)
 			if err == nil {
 				t.DisclosedVendors = segment
-				mapSegments[disclosedVendorsType] = true
+				mapSegments[SegmentTypeDisclosedVendors] = true
 			}
-		} else if segmentType == allowedVendorsType {
-			if mapSegments[allowedVendorsType] == true {
+		} else if segmentType == SegmentTypeAllowedVendors {
+			if mapSegments[SegmentTypeAllowedVendors] == true {
 				return nil, fmt.Errorf("duplicate Allowed Vendors segment")
 			}
 			segment, err := DecodeAllowedVendors(v)
 			if err == nil {
 				t.AllowedVendors = segment
-				mapSegments[allowedVendorsType] = true
+				mapSegments[SegmentTypeAllowedVendors] = true
 			}
-		} else if segmentType == publicherTCType {
-			if mapSegments[publicherTCType] == true {
+		} else if segmentType == SegmentTypePublisherTC {
+			if mapSegments[SegmentTypePublisherTC] == true {
 				return nil, fmt.Errorf("duplicate Publisher TC segment")
 			}
 			segment, err := DecodePublisherTC(v)
 			if err == nil {
 				t.PublisherTC = segment
-				mapSegments[publicherTCType] = true
+				mapSegments[SegmentTypePublisherTC] = true
 			}
 		} else {
-			if mapSegments[coreStringType] == true {
+			if mapSegments[SegmentTypeCoreString] == true {
 				return nil, fmt.Errorf("duplicate Core String segment")
 			}
 			segment, err := DecodeCoreString(v)
 			if err == nil {
 				t.CoreString = segment
 				if i == 0 {
-					mapSegments[coreStringType] = true
+					mapSegments[SegmentTypeCoreString] = true
 				}
 			}
 		}
 	}
 
-	if mapSegments[coreStringType] == false {
+	if mapSegments[SegmentTypeCoreString] == false {
 		return nil, fmt.Errorf("invalid TC string")
 	}
 
diff --git a/decode_test.go b/decode_test.go
index 0ff5f91..99d34dd 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -11,8 +11,8 @@ func TestGetVersion(t *testing.T) {
 		return
 	}
 
-	if version != 1 {
-		t.Errorf("Version should be 1")
+	if version != TcfVersion1 {
+		t.Errorf("Version should be %d", TcfVersion1)
 	}
 
 	version, err = GetVersion("COxR03kOxR1CqBcABCENAgCMAP_AAH_AAAqIF3EXySoGY2thI2YVFxBEIYwfJxyigMgChgQIsSwNQIeFLBoGLiAAHBGYJAQAGBAEEACBAQIkHGBMCQAAgAgBiRCMQEGMCzNIBIBAggEbY0FACCVmHkHSmZCY7064O__QLuIJEFQMAkSBAIACLECIQwAQDiAAAYAlAAABAhIaAAgIWBQEeAAAACAwAAgAAABBAAACAAQAAICIAAABAAAgAiAQAAAAGgIQAACBABACRIAAAEANCAAgiCEAQg4EAo4AAA")
@@ -21,8 +21,8 @@ func TestGetVersion(t *testing.T) {
 		return
 	}
 
-	if version != 2 {
-		t.Errorf("Version should be 2")
+	if version != TcfVersion2 {
+		t.Errorf("Version should be %d", TcfVersion2)
 	}
 }
 
@@ -35,8 +35,8 @@ func TestGetSegmentType(t *testing.T) {
 		return
 	}
 
-	if segType != 1 {
-		t.Errorf("Segment type should be 1")
+	if segType != SegmentTypeDisclosedVendors {
+		t.Errorf("Segment type should be %d", SegmentTypeDisclosedVendors)
 	}
 }
 
@@ -114,8 +114,8 @@ func TestDecodeCoreString(t *testing.T) {
 		return
 	}
 
-	if segType != 0 {
-		t.Errorf("Segment type should be 0")
+	if segType != SegmentTypeCoreString {
+		t.Errorf("Segment type should be %d", SegmentTypeCoreString)
 		return
 	}
 
@@ -145,8 +145,8 @@ func TestDecodeDisclosedVendors(t *testing.T) {
 		return
 	}
 
-	if segType != 1 {
-		t.Errorf("Segment type should be 1")
+	if segType != SegmentTypeDisclosedVendors {
+		t.Errorf("Segment type should be %d", SegmentTypeDisclosedVendors)
 		return
 	}
 
@@ -186,8 +186,8 @@ func TestDecodeAllowedVendors(t *testing.T) {
 		return
 	}
 
-	if segType != 2 {
-		t.Errorf("Segment type should be 2")
+	if segType != SegmentTypeAllowedVendors {
+		t.Errorf("Segment type should be %d", SegmentTypeAllowedVendors)
 		return
 	}
 
@@ -227,8 +227,8 @@ func TestDecodePublisherTC(t *testing.T) {
 		return
 	}
 
-	if segType != 3 {
-		t.Errorf("Segment type should be 3")
+	if segType != SegmentTypePublisherTC {
+		t.Errorf("Segment type should be %d", SegmentTypePublisherTC)
 		return
 	}
 
diff --git a/tcdata.go b/tcdata.go
index 0e363eb..e448a7c 100644
--- a/tcdata.go
+++ b/tcdata.go
@@ -2,13 +2,6 @@ package iabtcfv2
 
 import "strings"
 
-const (
-	coreStringType       = 0
-	disclosedVendorsType = 1
-	allowedVendorsType   = 2
-	publicherTCType      = 3
-)
-
 type TCData struct {
 	CoreString       *CoreString
 	DisclosedVendors *DisclosedVendors