diff --git a/schema.go b/schema.go
index 7ce5471c..cc462af2 100644
--- a/schema.go
+++ b/schema.go
@@ -100,31 +100,31 @@ func (r *AuthnRequest) Element() *etree.Element {
 }
 
 // MarshalXML implements xml.Marshaler
-func (a *AuthnRequest) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+func (r *AuthnRequest) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
 	type Alias AuthnRequest
 	aux := &struct {
 		IssueInstant RelaxedTime `xml:",attr"`
 		*Alias
 	}{
-		IssueInstant: RelaxedTime(a.IssueInstant),
-		Alias:        (*Alias)(a),
+		IssueInstant: RelaxedTime(r.IssueInstant),
+		Alias:        (*Alias)(r),
 	}
 	return e.Encode(aux)
 }
 
 // UnmarshalXML implements xml.Unmarshaler
-func (a *AuthnRequest) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+func (r *AuthnRequest) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	type Alias AuthnRequest
 	aux := &struct {
 		IssueInstant RelaxedTime `xml:",attr"`
 		*Alias
 	}{
-		Alias: (*Alias)(a),
+		Alias: (*Alias)(r),
 	}
 	if err := d.DecodeElement(&aux, &start); err != nil {
 		return err
 	}
-	a.IssueInstant = time.Time(aux.IssueInstant)
+	r.IssueInstant = time.Time(aux.IssueInstant)
 	return nil
 }
 
diff --git a/service_provider.go b/service_provider.go
index 76a5b3ca..1043d01c 100644
--- a/service_provider.go
+++ b/service_provider.go
@@ -25,6 +25,7 @@ import (
 // NameIDFormat is the format of the id
 type NameIDFormat string
 
+// Element returns an XML element representation of n.
 func (n NameIDFormat) Element() *etree.Element {
 	el := etree.NewElement("")
 	el.SetText(string(n))
diff --git a/time.go b/time.go
index 00ce754c..3f266f97 100644
--- a/time.go
+++ b/time.go
@@ -2,10 +2,13 @@ package saml
 
 import "time"
 
+// RelaxedTime is a version of time.Time that supports the time format
+// found in SAML documents.
 type RelaxedTime time.Time
 
 const timeFormat = "2006-01-02T15:04:05.999Z07:00"
 
+// MarshalText implements encoding.TextMarshaler
 func (m RelaxedTime) MarshalText() ([]byte, error) {
 	// According to section 1.2.2 of the OASIS SAML 1.1 spec, we can't trust
 	// other applications to handle time resolution finer than a millisecond.
@@ -18,6 +21,7 @@ func (m RelaxedTime) String() string {
 	return time.Time(m).Round(time.Millisecond).UTC().Format(timeFormat)
 }
 
+// UnmarshalText implements encoding.TextUnmarshaler
 func (m *RelaxedTime) UnmarshalText(text []byte) error {
 	if len(text) == 0 {
 		*m = RelaxedTime(time.Time{})