diff --git a/bench_test.go b/bench_test.go
index 5a999ee8..40520d57 100644
--- a/bench_test.go
+++ b/bench_test.go
@@ -48,16 +48,16 @@ func createNarrowTestData(b *testing.B, conn *Connection) {
 
 func removeBinaryEncoders() (encoders map[Oid]func(*MessageReader, int32) interface{}) {
 	encoders = make(map[Oid]func(*MessageReader, int32) interface{})
-	for k, v := range valueTranscoders {
+	for k, v := range ValueTranscoders {
 		encoders[k] = v.DecodeBinary
-		valueTranscoders[k].DecodeBinary = nil
+		ValueTranscoders[k].DecodeBinary = nil
 	}
 	return
 }
 
 func restoreBinaryEncoders(encoders map[Oid]func(*MessageReader, int32) interface{}) {
 	for k, v := range encoders {
-		valueTranscoders[k].DecodeBinary = v
+		ValueTranscoders[k].DecodeBinary = v
 	}
 }
 
diff --git a/connection.go b/connection.go
index cbebd2fb..8a6020a6 100644
--- a/connection.go
+++ b/connection.go
@@ -310,7 +310,7 @@ func (c *Connection) Prepare(name, sql string) (err error) {
 				ps.FieldDescriptions = c.rxRowDescription(r)
 				for i := range ps.FieldDescriptions {
 					oid := ps.FieldDescriptions[i].DataType
-					if valueTranscoders[oid] != nil && valueTranscoders[oid].DecodeBinary != nil {
+					if ValueTranscoders[oid] != nil && ValueTranscoders[oid].DecodeBinary != nil {
 						ps.FieldDescriptions[i].FormatCode = 1
 					}
 				}
@@ -375,7 +375,7 @@ func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...inter
 	w.writeCString(ps.Name)
 	w.write(int16(len(ps.ParameterOids)))
 	for _, oid := range ps.ParameterOids {
-		transcoder := valueTranscoders[oid]
+		transcoder := ValueTranscoders[oid]
 		if transcoder == nil {
 			transcoder = defaultTranscoder
 		}
@@ -384,7 +384,7 @@ func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...inter
 
 	w.write(int16(len(arguments)))
 	for i, oid := range ps.ParameterOids {
-		transcoder := valueTranscoders[oid]
+		transcoder := ValueTranscoders[oid]
 		if transcoder == nil {
 			transcoder = defaultTranscoder
 		}
@@ -393,7 +393,7 @@ func (c *Connection) sendPreparedQuery(ps *preparedStatement, arguments ...inter
 
 	w.write(int16(len(ps.FieldDescriptions)))
 	for _, fd := range ps.FieldDescriptions {
-		transcoder := valueTranscoders[fd.DataType]
+		transcoder := ValueTranscoders[fd.DataType]
 		if transcoder != nil && transcoder.DecodeBinary != nil {
 			w.write(int16(1))
 		} else {
diff --git a/data_row_reader.go b/data_row_reader.go
index 6684177d..dd557361 100644
--- a/data_row_reader.go
+++ b/data_row_reader.go
@@ -27,7 +27,7 @@ func (r *DataRowReader) ReadValue() interface{} {
 
 	size := r.mr.ReadInt32()
 	if size > -1 {
-		if vt, present := valueTranscoders[fieldDescription.DataType]; present {
+		if vt, present := ValueTranscoders[fieldDescription.DataType]; present {
 			switch fieldDescription.FormatCode {
 			case 0:
 				return vt.DecodeText(r.mr, size)
diff --git a/value_transcoder.go b/value_transcoder.go
index 27725d96..9614ea58 100644
--- a/value_transcoder.go
+++ b/value_transcoder.go
@@ -7,77 +7,89 @@ import (
 	"unsafe"
 )
 
-type valueTranscoder struct {
-	DecodeText   func(*MessageReader, int32) interface{}
+// ValueTranscoder stores all the data necessary to encode and decode values from
+// a PostgreSQL server
+type ValueTranscoder struct {
+	// DecodeText decodes values returned from the server in text format
+	DecodeText func(*MessageReader, int32) interface{}
+	// DecodeBinary decodes values returned from the server in binary format
 	DecodeBinary func(*MessageReader, int32) interface{}
-	EncodeTo     func(*messageWriter, interface{})
+	// EncodeTo encodes values to send to the server
+	EncodeTo func(*messageWriter, interface{})
+	// EncodeFormat is the format values are encoded for transmission.
+	// 0 = text
+	// 1 = binary
 	EncodeFormat int16
 }
 
-var valueTranscoders map[Oid]*valueTranscoder
-var defaultTranscoder *valueTranscoder
+// ValueTranscoders is used to transcode values being sent to and received from
+// the PostgreSQL server. Additional types can be transcoded by adding a
+// *ValueTranscoder for the appropriate Oid to the map.
+var ValueTranscoders map[Oid]*ValueTranscoder
+
+var defaultTranscoder *ValueTranscoder
 
 func init() {
-	valueTranscoders = make(map[Oid]*valueTranscoder)
+	ValueTranscoders = make(map[Oid]*ValueTranscoder)
 
 	// bool
-	valueTranscoders[Oid(16)] = &valueTranscoder{
+	ValueTranscoders[Oid(16)] = &ValueTranscoder{
 		DecodeText:   decodeBoolFromText,
 		DecodeBinary: decodeBoolFromBinary,
 		EncodeTo:     encodeBool,
 		EncodeFormat: 1}
 
 	// bytea
-	valueTranscoders[Oid(17)] = &valueTranscoder{
+	ValueTranscoders[Oid(17)] = &ValueTranscoder{
 		DecodeText:   decodeByteaFromText,
 		EncodeTo:     encodeBytea,
 		EncodeFormat: 1}
 
 	// int8
-	valueTranscoders[Oid(20)] = &valueTranscoder{
+	ValueTranscoders[Oid(20)] = &ValueTranscoder{
 		DecodeText:   decodeInt8FromText,
 		DecodeBinary: decodeInt8FromBinary,
 		EncodeTo:     encodeInt8,
 		EncodeFormat: 1}
 
 	// int2
-	valueTranscoders[Oid(21)] = &valueTranscoder{
+	ValueTranscoders[Oid(21)] = &ValueTranscoder{
 		DecodeText:   decodeInt2FromText,
 		DecodeBinary: decodeInt2FromBinary,
 		EncodeTo:     encodeInt2,
 		EncodeFormat: 1}
 
 	// int4
-	valueTranscoders[Oid(23)] = &valueTranscoder{
+	ValueTranscoders[Oid(23)] = &ValueTranscoder{
 		DecodeText:   decodeInt4FromText,
 		DecodeBinary: decodeInt4FromBinary,
 		EncodeTo:     encodeInt4,
 		EncodeFormat: 1}
 
 	// text
-	valueTranscoders[Oid(25)] = &valueTranscoder{
+	ValueTranscoders[Oid(25)] = &ValueTranscoder{
 		DecodeText: decodeTextFromText,
 		EncodeTo:   encodeText}
 
 	// float4
-	valueTranscoders[Oid(700)] = &valueTranscoder{
+	ValueTranscoders[Oid(700)] = &ValueTranscoder{
 		DecodeText:   decodeFloat4FromText,
 		DecodeBinary: decodeFloat4FromBinary,
 		EncodeTo:     encodeFloat4,
 		EncodeFormat: 1}
 
 	// float8
-	valueTranscoders[Oid(701)] = &valueTranscoder{
+	ValueTranscoders[Oid(701)] = &ValueTranscoder{
 		DecodeText:   decodeFloat8FromText,
 		DecodeBinary: decodeFloat8FromBinary,
 		EncodeTo:     encodeFloat8,
 		EncodeFormat: 1}
 
 	// varchar -- same as text
-	valueTranscoders[Oid(1043)] = valueTranscoders[Oid(25)]
+	ValueTranscoders[Oid(1043)] = ValueTranscoders[Oid(25)]
 
 	// use text transcoder for anything we don't understand
-	defaultTranscoder = valueTranscoders[Oid(25)]
+	defaultTranscoder = ValueTranscoders[Oid(25)]
 }
 
 func decodeBoolFromText(mr *MessageReader, size int32) interface{} {