diff --git a/jdr/type.go b/jdr/type.go
index 93aaf6f..c61939b 100644
--- a/jdr/type.go
+++ b/jdr/type.go
@@ -12,7 +12,8 @@ var regexp_d = regexp.MustCompile(`^[1-9][0-9]*d([468]|1[02]|20|100)$`)
 
 type VariableType interface {
     Name() string
-    Validate(s string) bool
+    Validate(value string) bool
+    DefaultValue() string
 }
 
 type VariableType_badType struct {}
@@ -25,6 +26,10 @@ func (*VariableType_badType) Validate(s string) bool {
     return false
 }
 
+func (*VariableType_badType) DefaultValue() string {
+    return ""
+}
+
 type VariableType_bool struct {}
 
 func (*VariableType_bool) Name() string {
@@ -47,6 +52,10 @@ func (self *VariableType_bool) Validate(value string) bool {
     return err == nil
 }
 
+func (self *VariableType_bool) DefaultValue() string {
+    return "false"
+}
+
 type VariableType_int struct {}
 
 func (*VariableType_int) Name() string {
@@ -62,6 +71,10 @@ func (self *VariableType_int) Validate(value string) bool {
     return err == nil
 }
 
+func (self *VariableType_int) DefaultValue() string {
+    return "0"
+}
+
 type VariableType_float struct {}
 
 func (*VariableType_float) Name() string {
@@ -77,6 +90,10 @@ func (self *VariableType_float) Validate(value string) bool {
     return err == nil
 }
 
+func (self *VariableType_float) DefaultValue() string {
+    return "0.0"
+}
+
 type VariableType_string struct {}
 
 func (*VariableType_string) Name() string {
@@ -87,6 +104,10 @@ func (*VariableType_string) Validate(s string) bool {
     return true
 }
 
+func (self *VariableType_string) DefaultValue() string {
+    return ""
+}
+
 type VariableType_d struct {}
 
 func (*VariableType_d) Name() string {
@@ -97,6 +118,11 @@ func (*VariableType_d) Validate(s string) bool {
     return regexp_d.MatchString(s)
 }
 
+func (self *VariableType_d) DefaultValue() string {
+    //FIXME: non-generic version
+    return ""
+}
+
 func makeVariableType(s string) VariableType {
     switch(strings.ToLower(s)) {
     case "bool":
@@ -125,18 +151,27 @@ func (self *CustomEnum) Name() string {
     return self.name
 }
 
-func (self *CustomEnum) Validate(s string) bool {
-    if !self.BaseType.Validate(s) {
-        return false
+func (self *CustomEnum) ToId(value string) (int, error) {
+    if !self.BaseType.Validate(value) {
+        return 0, errors.New("Invalid value")
     }
 
     for i := 0; i < len(self.Values); i++ {
-        if self.Values[i] == s {
-            return true
+        if self.Values[i] == value {
+            return i, nil
         }
     }
 
-    return false
+    return 0, errors.New("No such element")
+}
+
+func (self *CustomEnum) Validate(value string) bool {
+    _, err := self.ToId(value)
+    return err == nil
+}
+
+func (self *CustomEnum) DefaultValue() string {
+    return ""
 }
 
 type CustomStruct struct {
@@ -154,6 +189,11 @@ func (self *CustomStruct) Validate(s string) bool {
     return false
 }
 
+func (self *CustomStruct) DefaultValue() string {
+    //FIXME: non-generic version
+    return ""
+}
+
 func parseCustomEnum(root xmlNode) (*CustomEnum, error) {
     customEnum := CustomEnum {}