diff --git a/edns.go b/edns.go
index c1bbdaae2..0447fd826 100644
--- a/edns.go
+++ b/edns.go
@@ -58,7 +58,7 @@ func makeDataOpt(code uint16) EDNS0 {
 	case EDNS0EDE:
 		return new(EDNS0_EDE)
 	case EDNS0ESU:
-		return &EDNS0_ESU{Code: EDNS0ESU}
+		return new(EDNS0_ESU)
 	default:
 		e := new(EDNS0_LOCAL)
 		e.Code = code
@@ -66,8 +66,7 @@ func makeDataOpt(code uint16) EDNS0 {
 	}
 }
 
-// OPT is the EDNS0 RR appended to messages to convey extra (meta) information.
-// See RFC 6891.
+// OPT is the EDNS0 RR appended to messages to convey extra (meta) information. See RFC 6891.
 type OPT struct {
 	Hdr    RR_Header
 	Option []EDNS0 `dns:"opt"`
@@ -144,8 +143,6 @@ func (*OPT) parse(c *zlexer, origin string) *ParseError {
 
 func (rr *OPT) isDuplicate(r2 RR) bool { return false }
 
-// return the old value -> delete SetVersion?
-
 // Version returns the EDNS version used. Only zero is defined.
 func (rr *OPT) Version() uint8 {
 	return uint8(rr.Hdr.Ttl & 0x00FF0000 >> 16)
@@ -236,8 +233,8 @@ type EDNS0 interface {
 //	e.Nsid = "AA"
 //	o.Option = append(o.Option, e)
 type EDNS0_NSID struct {
-	Code uint16 // Always EDNS0NSID
-	Nsid string // This string needs to be hex encoded
+	Code uint16 // always EDNS0NSID
+	Nsid string // string needs to be hex encoded
 }
 
 func (e *EDNS0_NSID) pack() ([]byte, error) {
@@ -275,7 +272,7 @@ func (e *EDNS0_NSID) copy() EDNS0           { return &EDNS0_NSID{e.Code, e.Nsid}
 // When packing it will apply SourceNetmask. If you need more advanced logic,
 // patches welcome and good luck.
 type EDNS0_SUBNET struct {
-	Code          uint16 // Always EDNS0SUBNET
+	Code          uint16 // always EDNS0SUBNET
 	Family        uint16 // 1 for IP, 2 for IP6
 	SourceNetmask uint8
 	SourceScope   uint8
@@ -399,8 +396,8 @@ func (e *EDNS0_SUBNET) copy() EDNS0 {
 //
 // There is no guarantee that the Cookie string has a specific length.
 type EDNS0_COOKIE struct {
-	Code   uint16 // Always EDNS0COOKIE
-	Cookie string // Hex-encoded cookie data
+	Code   uint16 // always EDNS0COOKIE
+	Cookie string // hex encoded cookie data
 }
 
 func (e *EDNS0_COOKIE) pack() ([]byte, error) {
@@ -430,7 +427,7 @@ func (e *EDNS0_COOKIE) copy() EDNS0           { return &EDNS0_COOKIE{e.Code, e.C
 //	e.Lease = 120 // in seconds
 //	o.Option = append(o.Option, e)
 type EDNS0_UL struct {
-	Code     uint16 // Always EDNS0UL
+	Code     uint16 // always EDNS0UL
 	Lease    uint32
 	KeyLease uint32
 }
@@ -469,7 +466,7 @@ func (e *EDNS0_UL) unpack(b []byte) error {
 // EDNS0_LLQ stands for Long Lived Queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
 // Implemented for completeness, as the EDNS0 type code is assigned.
 type EDNS0_LLQ struct {
-	Code      uint16 // Always EDNS0LLQ
+	Code      uint16 // always EDNS0LLQ
 	Version   uint16
 	Opcode    uint16
 	Error     uint16
@@ -515,7 +512,7 @@ func (e *EDNS0_LLQ) copy() EDNS0 {
 
 // EDNS0_DAU implements the EDNS0 "DNSSEC Algorithm Understood" option. See RFC 6975.
 type EDNS0_DAU struct {
-	Code    uint16 // Always EDNS0DAU
+	Code    uint16 // always EDNS0DAU
 	AlgCode []uint8
 }
 
@@ -539,7 +536,7 @@ func (e *EDNS0_DAU) copy() EDNS0 { return &EDNS0_DAU{e.Code, e.AlgCode} }
 
 // EDNS0_DHU implements the EDNS0 "DS Hash Understood" option. See RFC 6975.
 type EDNS0_DHU struct {
-	Code    uint16 // Always EDNS0DHU
+	Code    uint16 // always EDNS0DHU
 	AlgCode []uint8
 }
 
@@ -563,7 +560,7 @@ func (e *EDNS0_DHU) copy() EDNS0 { return &EDNS0_DHU{e.Code, e.AlgCode} }
 
 // EDNS0_N3U implements the EDNS0 "NSEC3 Hash Understood" option. See RFC 6975.
 type EDNS0_N3U struct {
-	Code    uint16 // Always EDNS0N3U
+	Code    uint16 // always EDNS0N3U
 	AlgCode []uint8
 }
 
@@ -588,7 +585,7 @@ func (e *EDNS0_N3U) copy() EDNS0 { return &EDNS0_N3U{e.Code, e.AlgCode} }
 
 // EDNS0_EXPIRE implements the EDNS0 option as described in RFC 7314.
 type EDNS0_EXPIRE struct {
-	Code   uint16 // Always EDNS0EXPIRE
+	Code   uint16 // always EDNS0EXPIRE
 	Expire uint32
 	Empty  bool // Empty is used to signal an empty Expire option in a backwards compatible way, it's not used on the wire.
 }
@@ -668,7 +665,7 @@ func (e *EDNS0_LOCAL) unpack(b []byte) error {
 // EDNS0_TCP_KEEPALIVE is an EDNS0 option that instructs the server to keep
 // the TCP connection alive. See RFC 7828.
 type EDNS0_TCP_KEEPALIVE struct {
-	Code uint16 // Always EDNSTCPKEEPALIVE
+	Code uint16 // always EDNSTCPKEEPALIVE
 
 	// Timeout is an idle timeout value for the TCP connection, specified in
 	// units of 100 milliseconds, encoded in network byte order. If set to 0,
@@ -839,13 +836,12 @@ func (e *EDNS0_EDE) unpack(b []byte) error {
 	return nil
 }
 
-// The EDNS0_ESU option for ENUM Source-URI Extension
+// The EDNS0_ESU option for ENUM Source-URI Extension.
 type EDNS0_ESU struct {
-	Code uint16
+	Code uint16 // always EDNS0ESU
 	Uri  string
 }
 
-// Option implements the EDNS0 interface.
 func (e *EDNS0_ESU) Option() uint16        { return EDNS0ESU }
 func (e *EDNS0_ESU) String() string        { return e.Uri }
 func (e *EDNS0_ESU) copy() EDNS0           { return &EDNS0_ESU{e.Code, e.Uri} }