diff --git a/listener.go b/listener.go
index b4c5623..2c15b40 100644
--- a/listener.go
+++ b/listener.go
@@ -8,7 +8,7 @@ type Listener interface {
 	CheckHost(ip net.IP, domain, sender string)
 	CheckHostResult(r Result, explanation string, extras *ResponseExtras, err error)
 	SPFRecord(s string)
-	Directive(unused bool, qualifier, mechanism, value, effectiveValue string)
+	Directive(unused bool, qualifier, mechanism, key, value, effectiveValue string)
 	NonMatch(qualifier, mechanism, value string, result Result, err error)
 	Match(qualifier, mechanism, value string, result Result, explanation string, extras *ResponseExtras, err error)
 	FirstMatch(r Result, err error)
diff --git a/parser.go b/parser.go
index b18ccc0..4f787d5 100644
--- a/parser.go
+++ b/parser.go
@@ -342,7 +342,7 @@ func (p *parser) fireDirective(t *token, effectiveValue string) {
 	if p.listener == nil {
 		return
 	}
-	p.listener.Directive(false, t.qualifier.String(), t.mechanism.String(), t.value, effectiveValue)
+	p.listener.Directive(false, t.qualifier.String(), t.mechanism.String(), t.key, t.value, effectiveValue)
 }
 
 func (p *parser) fireMatchingIP(t *token, fqdn string, ipn net.IPNet, host string, ip net.IP) {
@@ -356,7 +356,7 @@ func (p *parser) fireUnusedDirective(t *token) {
 	if p.listener == nil || t == nil {
 		return
 	}
-	p.listener.Directive(true, t.qualifier.String(), t.mechanism.String(), t.value, "")
+	p.listener.Directive(true, t.qualifier.String(), t.mechanism.String(), t.key, t.value, "")
 }
 
 func (p *parser) fireNonMatch(t *token, r Result, e error) {
diff --git a/printer/printer.go b/printer/printer.go
index 337bb2f..3cc4c6a 100644
--- a/printer/printer.go
+++ b/printer/printer.go
@@ -48,7 +48,7 @@ func (p *Printer) CheckHostResult(r spf.Result, explanation string, extras *spf.
 	fmt.Fprintf(p.w, "%s= %s, %v, %v, %v\n", strings.Repeat("  ", p.c), r, extras, explanation, err)
 }
 
-func (p *Printer) Directive(unused bool, qualifier, mechanism, value, effectiveValue string) {
+func (p *Printer) Directive(unused bool, qualifier, mechanism, key, value, effectiveValue string) {
 	fmt.Fprintf(p.w, "%s", strings.Repeat("  ", p.c))
 	if qualifier == "+" {
 		qualifier = ""
@@ -61,6 +61,11 @@ func (p *Printer) Directive(unused bool, qualifier, mechanism, value, effectiveV
 	if mechanism == "v" {
 		delimiter = "="
 	}
+
+	if mechanism[0] == ':' {
+		fmt.Fprintf(p.w, " (%s)", key)
+	}
+
 	if value != "" {
 		fmt.Fprintf(p.w, "%s%s", delimiter, value)
 	}
diff --git a/token.go b/token.go
index 3db179f..53f392b 100644
--- a/token.go
+++ b/token.go
@@ -6,6 +6,9 @@ import (
 	"strings"
 )
 
+// UnknownModifierMech constructed so we break policy if someone tries to create a policy out of mechanism string function instead of using actual key
+const UnknownModifierMech = ":?"
+
 type tokenType int
 
 const (
@@ -83,9 +86,9 @@ func (tok tokenType) String() string {
 	case qTilde:
 		return "~"
 	case tUnknownModifier:
-		return "UNKNOWN_MODIFIER"
+		return UnknownModifierMech
 	default:
-		return strconv.Itoa(int(tok))
+		return ":" + strconv.Itoa(int(tok))
 	}
 }
 
@@ -197,3 +200,7 @@ func (t *token) String() string {
 	}
 	return fmt.Sprintf("%s%s%s%s", q, k, d, t.value)
 }
+
+func IsKnownMechanism(s string) bool {
+	return tokenTypeFromString(s) != tErr
+}