diff --git a/cmd/serve/proto/doc.go b/cmd/serve/proto/doc.go
new file mode 100644
index 0000000..ecf00d2
--- /dev/null
+++ b/cmd/serve/proto/doc.go
@@ -0,0 +1,5 @@
+//go:generate protoc -I/usr/local/include -I. -I$GOPATH/src -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis --go_out=plugins=grpc:. serve.proto
+//go:generate protoc -I/usr/local/include -I. -I$GOPATH/src -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis --grpc-gateway_out=logtostderr=true:. serve.proto
+//go:generate protoc -I/usr/local/include -I. -I$GOPATH/src -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis --swagger_out=logtostderr=true:. serve.proto
+
+package serve
diff --git a/cmd/serve/proto/protoc.sh b/cmd/serve/proto/protoc.sh
deleted file mode 100755
index 5789440..0000000
--- a/cmd/serve/proto/protoc.sh
+++ /dev/null
@@ -1,18 +0,0 @@
-#!/bin/sh
-protoc -I/usr/local/include -I. \
-  -I$GOPATH/src \
-  -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
-  --go_out=plugins=grpc:. \
-  serve.proto
-
-protoc -I/usr/local/include -I. \
-  -I$GOPATH/src \
-  -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
-  --grpc-gateway_out=logtostderr=true:. \
-  serve.proto
-
-protoc -I/usr/local/include -I. \
-  -I$GOPATH/src \
-  -I$GOPATH/src/github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis \
-  --swagger_out=logtostderr=true:. \
-  serve.proto
diff --git a/cmd/serve/proto/serve.pb.go b/cmd/serve/proto/serve.pb.go
index 5c36ac6..7b5228a 100644
--- a/cmd/serve/proto/serve.pb.go
+++ b/cmd/serve/proto/serve.pb.go
@@ -12,8 +12,6 @@ It has these top-level messages:
 	GetFileResponse
 	GetAnnotationsRequest
 	GetAnnotationsResponse
-	Annotation
-	Location
 */
 package serve
 
@@ -21,6 +19,7 @@ import proto "github.com/golang/protobuf/proto"
 import fmt "fmt"
 import math "math"
 import _ "google.golang.org/genproto/googleapis/api/annotations"
+import goref_proto "github.com/korfuri/goref/proto"
 
 import (
 	context "golang.org/x/net/context"
@@ -38,39 +37,6 @@ var _ = math.Inf
 // proto package needs to be updated.
 const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
 
-type Type int32
-
-const (
-	Type_Instantiation  Type = 0
-	Type_Call           Type = 1
-	Type_Implementation Type = 2
-	Type_Extension      Type = 3
-	Type_Import         Type = 4
-	Type_Reference      Type = 5
-)
-
-var Type_name = map[int32]string{
-	0: "Instantiation",
-	1: "Call",
-	2: "Implementation",
-	3: "Extension",
-	4: "Import",
-	5: "Reference",
-}
-var Type_value = map[string]int32{
-	"Instantiation":  0,
-	"Call":           1,
-	"Implementation": 2,
-	"Extension":      3,
-	"Import":         4,
-	"Reference":      5,
-}
-
-func (x Type) String() string {
-	return proto.EnumName(Type_name, int32(x))
-}
-func (Type) EnumDescriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
-
 type GetFileRequest struct {
 	Path string `protobuf:"bytes,1,opt,name=path" json:"path,omitempty"`
 }
@@ -128,8 +94,8 @@ func (m *GetAnnotationsRequest) GetPath() string {
 }
 
 type GetAnnotationsResponse struct {
-	Path       string        `protobuf:"bytes,1,opt,name=path" json:"path,omitempty"`
-	Annotation []*Annotation `protobuf:"bytes,2,rep,name=annotation" json:"annotation,omitempty"`
+	Path       string             `protobuf:"bytes,1,opt,name=path" json:"path,omitempty"`
+	Annotation []*goref_proto.Ref `protobuf:"bytes,2,rep,name=annotation" json:"annotation,omitempty"`
 }
 
 func (m *GetAnnotationsResponse) Reset()                    { *m = GetAnnotationsResponse{} }
@@ -144,109 +110,18 @@ func (m *GetAnnotationsResponse) GetPath() string {
 	return ""
 }
 
-func (m *GetAnnotationsResponse) GetAnnotation() []*Annotation {
+func (m *GetAnnotationsResponse) GetAnnotation() []*goref_proto.Ref {
 	if m != nil {
 		return m.Annotation
 	}
 	return nil
 }
 
-type Annotation struct {
-	From *Location `protobuf:"bytes,1,opt,name=from" json:"from,omitempty"`
-	To   *Location `protobuf:"bytes,2,opt,name=to" json:"to,omitempty"`
-	Type Type      `protobuf:"varint,3,opt,name=type,enum=serve.Type" json:"type,omitempty"`
-}
-
-func (m *Annotation) Reset()                    { *m = Annotation{} }
-func (m *Annotation) String() string            { return proto.CompactTextString(m) }
-func (*Annotation) ProtoMessage()               {}
-func (*Annotation) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{4} }
-
-func (m *Annotation) GetFrom() *Location {
-	if m != nil {
-		return m.From
-	}
-	return nil
-}
-
-func (m *Annotation) GetTo() *Location {
-	if m != nil {
-		return m.To
-	}
-	return nil
-}
-
-func (m *Annotation) GetType() Type {
-	if m != nil {
-		return m.Type
-	}
-	return Type_Instantiation
-}
-
-type Location struct {
-	Package     string `protobuf:"bytes,1,opt,name=package" json:"package,omitempty"`
-	Filename    string `protobuf:"bytes,2,opt,name=filename" json:"filename,omitempty"`
-	StartLine   int64  `protobuf:"varint,3,opt,name=start_line,json=startLine" json:"start_line,omitempty"`
-	StartColumn int64  `protobuf:"varint,4,opt,name=start_column,json=startColumn" json:"start_column,omitempty"`
-	EndLine     int64  `protobuf:"varint,5,opt,name=end_line,json=endLine" json:"end_line,omitempty"`
-	EndColumn   int64  `protobuf:"varint,6,opt,name=end_column,json=endColumn" json:"end_column,omitempty"`
-}
-
-func (m *Location) Reset()                    { *m = Location{} }
-func (m *Location) String() string            { return proto.CompactTextString(m) }
-func (*Location) ProtoMessage()               {}
-func (*Location) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{5} }
-
-func (m *Location) GetPackage() string {
-	if m != nil {
-		return m.Package
-	}
-	return ""
-}
-
-func (m *Location) GetFilename() string {
-	if m != nil {
-		return m.Filename
-	}
-	return ""
-}
-
-func (m *Location) GetStartLine() int64 {
-	if m != nil {
-		return m.StartLine
-	}
-	return 0
-}
-
-func (m *Location) GetStartColumn() int64 {
-	if m != nil {
-		return m.StartColumn
-	}
-	return 0
-}
-
-func (m *Location) GetEndLine() int64 {
-	if m != nil {
-		return m.EndLine
-	}
-	return 0
-}
-
-func (m *Location) GetEndColumn() int64 {
-	if m != nil {
-		return m.EndColumn
-	}
-	return 0
-}
-
 func init() {
 	proto.RegisterType((*GetFileRequest)(nil), "serve.GetFileRequest")
 	proto.RegisterType((*GetFileResponse)(nil), "serve.GetFileResponse")
 	proto.RegisterType((*GetAnnotationsRequest)(nil), "serve.GetAnnotationsRequest")
 	proto.RegisterType((*GetAnnotationsResponse)(nil), "serve.GetAnnotationsResponse")
-	proto.RegisterType((*Annotation)(nil), "serve.Annotation")
-	proto.RegisterType((*Location)(nil), "serve.Location")
-	proto.RegisterEnum("serve.Type", Type_name, Type_value)
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
@@ -357,36 +232,25 @@ var _Goref_serviceDesc = grpc.ServiceDesc{
 func init() { proto.RegisterFile("serve.proto", fileDescriptor0) }
 
 var fileDescriptor0 = []byte{
-	// 495 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x7c, 0x53, 0x4d, 0x6f, 0xd3, 0x40,
-	0x10, 0xc5, 0x8e, 0xf3, 0x35, 0xa6, 0xa9, 0x3b, 0x52, 0x2b, 0x63, 0x35, 0x4a, 0x6a, 0x90, 0x88,
-	0x82, 0x54, 0xab, 0xe1, 0xcc, 0xa1, 0xaa, 0x20, 0x8a, 0xd4, 0x93, 0xc5, 0x89, 0x4b, 0xb5, 0x38,
-	0x93, 0x60, 0x61, 0xef, 0x1a, 0xef, 0x36, 0xa2, 0x42, 0x5c, 0xf8, 0x0b, 0xfc, 0x1d, 0xfe, 0x05,
-	0x47, 0xae, 0xfc, 0x10, 0xe4, 0x5d, 0xa7, 0x0e, 0xa5, 0xf4, 0xe6, 0x99, 0xf7, 0xde, 0x3c, 0xcf,
-	0xe8, 0x2d, 0xb8, 0x92, 0xca, 0x0d, 0x9d, 0x16, 0xa5, 0x50, 0x02, 0xdb, 0xba, 0x08, 0x8e, 0xd7,
-	0x42, 0xac, 0x33, 0x8a, 0x58, 0x91, 0x46, 0x8c, 0x73, 0xa1, 0x98, 0x4a, 0x05, 0x97, 0x86, 0x14,
-	0x3e, 0x83, 0xc1, 0x9c, 0xd4, 0x9b, 0x34, 0xa3, 0x98, 0x3e, 0x5d, 0x93, 0x54, 0x88, 0xe0, 0x14,
-	0x4c, 0x7d, 0xf0, 0xad, 0xb1, 0x35, 0xe9, 0xc7, 0xfa, 0x3b, 0x3c, 0x87, 0xfd, 0x5b, 0x96, 0x2c,
-	0x04, 0x97, 0x74, 0x1f, 0x0d, 0x03, 0xe8, 0x25, 0x82, 0x2b, 0xe2, 0x4a, 0xfa, 0xb6, 0xee, 0xdf,
-	0xd6, 0xe1, 0x0b, 0x38, 0x9c, 0x93, 0x3a, 0x6f, 0x7e, 0xe0, 0x21, 0xbf, 0x2b, 0x38, 0xba, 0x4b,
-	0x7e, 0xc0, 0xf6, 0x0c, 0xa0, 0x59, 0xcc, 0xb7, 0xc7, 0xad, 0x89, 0x3b, 0x3b, 0x38, 0x35, 0xa7,
-	0x68, 0x66, 0xc4, 0x3b, 0xa4, 0x50, 0x02, 0x34, 0x08, 0x3e, 0x05, 0x67, 0x55, 0x8a, 0x5c, 0x0f,
-	0x75, 0x67, 0xfb, 0xb5, 0xf4, 0x52, 0x24, 0x46, 0xa8, 0x41, 0x1c, 0x81, 0xad, 0x84, 0x5e, 0xeb,
-	0x1e, 0x8a, 0xad, 0x04, 0x8e, 0xc0, 0x51, 0x37, 0x05, 0xf9, 0xad, 0xb1, 0x35, 0x19, 0xcc, 0xdc,
-	0x9a, 0xf2, 0xf6, 0xa6, 0xa0, 0x58, 0x03, 0xe1, 0x0f, 0x0b, 0x7a, 0x5b, 0x05, 0xfa, 0xd0, 0x2d,
-	0x58, 0xf2, 0x91, 0xad, 0xa9, 0xde, 0x65, 0x5b, 0x56, 0x57, 0x5c, 0xa5, 0x19, 0x71, 0x96, 0xd3,
-	0xf6, 0x8a, 0xdb, 0x1a, 0x87, 0x00, 0x52, 0xb1, 0x52, 0x5d, 0x65, 0x29, 0x37, 0x4e, 0xad, 0xb8,
-	0xaf, 0x3b, 0x97, 0x29, 0x27, 0x3c, 0x81, 0xc7, 0x06, 0x4e, 0x44, 0x76, 0x9d, 0x73, 0xdf, 0xd1,
-	0x04, 0x57, 0xf7, 0x2e, 0x74, 0x0b, 0x9f, 0x40, 0x8f, 0xf8, 0xd2, 0xe8, 0xdb, 0x1a, 0xee, 0x12,
-	0x5f, 0x6a, 0xf5, 0x10, 0xa0, 0x82, 0x6a, 0x6d, 0xc7, 0x0c, 0x27, 0xbe, 0x34, 0xca, 0x29, 0x03,
-	0xa7, 0x5a, 0x06, 0x0f, 0x60, 0x6f, 0xc1, 0xa5, 0x62, 0x5c, 0xa5, 0x7a, 0x15, 0xef, 0x11, 0xf6,
-	0xc0, 0xb9, 0x60, 0x59, 0xe6, 0x59, 0x88, 0x30, 0x58, 0xe4, 0x45, 0x46, 0x39, 0x71, 0x73, 0x5c,
-	0xcf, 0xc6, 0x3d, 0xe8, 0xbf, 0xfe, 0xac, 0x88, 0xcb, 0xaa, 0x6c, 0x21, 0x40, 0x67, 0x91, 0x17,
-	0xa2, 0x54, 0x9e, 0x53, 0x41, 0x31, 0xad, 0xa8, 0x24, 0x9e, 0x90, 0xd7, 0x9e, 0xfd, 0xb2, 0xa0,
-	0x3d, 0x17, 0x25, 0xad, 0xf0, 0x1d, 0x74, 0xeb, 0xc4, 0xe1, 0x61, 0x7d, 0xc9, 0xbf, 0x73, 0x1a,
-	0x1c, 0xdd, 0x6d, 0x9b, 0x84, 0x84, 0xe3, 0x6f, 0x3f, 0x7f, 0x7f, 0xb7, 0x03, 0xf4, 0xa3, 0xcd,
-	0x59, 0xb4, 0xae, 0x86, 0x45, 0xd5, 0xf9, 0xa2, 0x2f, 0x55, 0x56, 0x5e, 0x4d, 0xa7, 0x5f, 0x71,
-	0xa3, 0x33, 0xbf, 0x93, 0x2e, 0x3c, 0x6e, 0x66, 0xfd, 0x9b, 0xd0, 0x60, 0xf8, 0x1f, 0xb4, 0x36,
-	0x7c, 0xae, 0x0d, 0x4f, 0x70, 0xd4, 0x18, 0xee, 0xbc, 0xb3, 0xc6, 0xf7, 0x7d, 0x47, 0x3f, 0xb9,
-	0x97, 0x7f, 0x02, 0x00, 0x00, 0xff, 0xff, 0xa3, 0x19, 0x3e, 0x37, 0xa6, 0x03, 0x00, 0x00,
+	// 306 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x7c, 0x91, 0xcf, 0x4a, 0xf3, 0x40,
+	0x14, 0xc5, 0x69, 0xbe, 0xaf, 0xfe, 0x99, 0x82, 0xca, 0x40, 0x4b, 0x18, 0x2a, 0xc6, 0x20, 0x18,
+	0x2a, 0x64, 0xb4, 0xae, 0x5d, 0x74, 0x63, 0xf6, 0x59, 0xba, 0x10, 0xd2, 0x72, 0x93, 0x0e, 0xc6,
+	0xb9, 0x71, 0x66, 0x92, 0x8d, 0xb8, 0xf1, 0x15, 0x7c, 0x34, 0x97, 0x6e, 0x7d, 0x10, 0xe9, 0x24,
+	0x34, 0xb1, 0x6a, 0x77, 0xb9, 0xf7, 0x1e, 0x72, 0xce, 0xf9, 0x0d, 0x19, 0x68, 0x50, 0x15, 0x84,
+	0x85, 0x42, 0x83, 0xb4, 0x6f, 0x07, 0x36, 0xce, 0x10, 0xb3, 0x1c, 0x78, 0x52, 0x08, 0x9e, 0x48,
+	0x89, 0x26, 0x31, 0x02, 0xa5, 0xae, 0x45, 0x2c, 0xc8, 0x84, 0x59, 0x96, 0xf3, 0x70, 0x81, 0x8f,
+	0xfc, 0x01, 0x55, 0x5a, 0x2a, 0xc1, 0x33, 0x54, 0x90, 0x72, 0x7b, 0xe7, 0x0a, 0xd2, 0x5a, 0xe9,
+	0x9f, 0x91, 0x83, 0x08, 0xcc, 0xad, 0xc8, 0x21, 0x86, 0xa7, 0x12, 0xb4, 0xa1, 0x94, 0xfc, 0x2f,
+	0x12, 0xb3, 0x74, 0x7b, 0x5e, 0x2f, 0xd8, 0x8f, 0xed, 0xb7, 0x3f, 0x23, 0x87, 0x6b, 0x95, 0x2e,
+	0x50, 0x6a, 0xf8, 0x4d, 0x46, 0x19, 0xd9, 0x5b, 0xa0, 0x34, 0x20, 0x8d, 0x76, 0x1d, 0xbb, 0x5f,
+	0xcf, 0xfe, 0x05, 0x19, 0x46, 0x60, 0x66, 0x6d, 0xd4, 0x6d, 0x7e, 0xf7, 0x64, 0xb4, 0x29, 0xde,
+	0x62, 0x7b, 0x49, 0x48, 0x8b, 0xc0, 0x75, 0xbc, 0x7f, 0xc1, 0x60, 0x7a, 0x14, 0xda, 0xbe, 0x75,
+	0xcb, 0x30, 0x86, 0x34, 0xee, 0x68, 0xa6, 0x1f, 0x3d, 0xd2, 0x8f, 0x56, 0x77, 0x7a, 0x47, 0x76,
+	0x9b, 0x66, 0x74, 0x18, 0xd6, 0x9c, 0xbf, 0xf3, 0x60, 0xa3, 0xcd, 0x75, 0x9d, 0xc4, 0xf7, 0x5e,
+	0xdf, 0x3f, 0xdf, 0x1c, 0x46, 0x5d, 0x5e, 0x5d, 0x35, 0x70, 0x53, 0x91, 0x03, 0x7f, 0x5e, 0x65,
+	0xba, 0x99, 0x4c, 0x5e, 0x68, 0x65, 0xd9, 0x76, 0x5a, 0xd0, 0x71, 0xfb, 0xaf, 0x9f, 0x24, 0xd8,
+	0xf1, 0x1f, 0xd7, 0xc6, 0xf0, 0xdc, 0x1a, 0x9e, 0xd2, 0x93, 0xd6, 0xb0, 0xf3, 0xf2, 0xad, 0xef,
+	0x7c, 0xc7, 0x96, 0xbe, 0xfe, 0x0a, 0x00, 0x00, 0xff, 0xff, 0x02, 0x36, 0x8d, 0x60, 0x38, 0x02,
+	0x00, 0x00,
 }
diff --git a/cmd/serve/proto/serve.proto b/cmd/serve/proto/serve.proto
index c2c227c..0670776 100644
--- a/cmd/serve/proto/serve.proto
+++ b/cmd/serve/proto/serve.proto
@@ -1,6 +1,7 @@
 syntax = "proto3";
 
 import "google/api/annotations.proto";
+import "github.com/korfuri/goref/proto/ref.proto";
 
 package serve;
 
@@ -19,31 +20,7 @@ message GetAnnotationsRequest {
 
 message GetAnnotationsResponse {
   string path = 1;
-  repeated Annotation annotation = 2;
-}
-
-message Annotation {
-  Location from = 1;
-  Location to = 2;
-  Type type = 3;
-}
-
-message Location {
-  string package = 1;
-  string filename = 2;
-  int64 start_line = 3;
-  int64 start_column = 4;
-  int64 end_line = 5;
-  int64 end_column = 6;
-}
-
-enum Type {
-  Instantiation = 0;
-  Call = 1;
-  Implementation = 2;
-  Extension = 3;
-  Import = 4;
-  Reference = 5;
+  repeated goref.proto.Ref annotation = 2;
 }
 
 service Goref {
diff --git a/cmd/serve/proto/serve.swagger.json b/cmd/serve/proto/serve.swagger.json
index 50bd22d..6c45e00 100644
--- a/cmd/serve/proto/serve.swagger.json
+++ b/cmd/serve/proto/serve.swagger.json
@@ -65,17 +65,71 @@
     }
   },
   "definitions": {
-    "serveAnnotation": {
+    "gorefprotoLocation": {
       "type": "object",
       "properties": {
+        "position": {
+          "$ref": "#/definitions/protoPosition"
+        },
+        "package": {
+          "type": "string"
+        },
+        "ident": {
+          "type": "string"
+        }
+      }
+    },
+    "gorefprotoType": {
+      "type": "string",
+      "enum": [
+        "Instantiation",
+        "Call",
+        "Implementation",
+        "Extension",
+        "Import",
+        "Reference"
+      ],
+      "default": "Instantiation"
+    },
+    "protoPosition": {
+      "type": "object",
+      "properties": {
+        "filename": {
+          "type": "string"
+        },
+        "start_line": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "start_col": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "end_line": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "end_col": {
+          "type": "integer",
+          "format": "int32"
+        }
+      }
+    },
+    "protoRef": {
+      "type": "object",
+      "properties": {
+        "version": {
+          "type": "string",
+          "format": "int64"
+        },
         "from": {
-          "$ref": "#/definitions/serveLocation"
+          "$ref": "#/definitions/gorefprotoLocation"
         },
         "to": {
-          "$ref": "#/definitions/serveLocation"
+          "$ref": "#/definitions/gorefprotoLocation"
         },
         "type": {
-          "$ref": "#/definitions/serveType"
+          "$ref": "#/definitions/gorefprotoType"
         }
       }
     },
@@ -88,7 +142,7 @@
         "annotation": {
           "type": "array",
           "items": {
-            "$ref": "#/definitions/serveAnnotation"
+            "$ref": "#/definitions/protoRef"
           }
         }
       }
@@ -103,45 +157,6 @@
           "type": "string"
         }
       }
-    },
-    "serveLocation": {
-      "type": "object",
-      "properties": {
-        "package": {
-          "type": "string"
-        },
-        "filename": {
-          "type": "string"
-        },
-        "start_line": {
-          "type": "string",
-          "format": "int64"
-        },
-        "start_column": {
-          "type": "string",
-          "format": "int64"
-        },
-        "end_line": {
-          "type": "string",
-          "format": "int64"
-        },
-        "end_column": {
-          "type": "string",
-          "format": "int64"
-        }
-      }
-    },
-    "serveType": {
-      "type": "string",
-      "enum": [
-        "Instantiation",
-        "Call",
-        "Implementation",
-        "Extension",
-        "Import",
-        "Reference"
-      ],
-      "default": "Instantiation"
     }
   }
 }
diff --git a/proto/doc.go b/proto/doc.go
new file mode 100644
index 0000000..8618fea
--- /dev/null
+++ b/proto/doc.go
@@ -0,0 +1,3 @@
+//go:generate protoc --go_out=. ref.proto
+
+package goref_proto
diff --git a/proto/ref.pb.go b/proto/ref.pb.go
new file mode 100644
index 0000000..d4d9446
--- /dev/null
+++ b/proto/ref.pb.go
@@ -0,0 +1,218 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: ref.proto
+
+/*
+Package goref_proto is a generated protocol buffer package.
+
+It is generated from these files:
+	ref.proto
+
+It has these top-level messages:
+	Ref
+	Location
+	Position
+*/
+package goref_proto
+
+import proto "github.com/golang/protobuf/proto"
+import fmt "fmt"
+import math "math"
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
+
+type Type int32
+
+const (
+	Type_Instantiation  Type = 0
+	Type_Call           Type = 1
+	Type_Implementation Type = 2
+	Type_Extension      Type = 3
+	Type_Import         Type = 4
+	Type_Reference      Type = 5
+)
+
+var Type_name = map[int32]string{
+	0: "Instantiation",
+	1: "Call",
+	2: "Implementation",
+	3: "Extension",
+	4: "Import",
+	5: "Reference",
+}
+var Type_value = map[string]int32{
+	"Instantiation":  0,
+	"Call":           1,
+	"Implementation": 2,
+	"Extension":      3,
+	"Import":         4,
+	"Reference":      5,
+}
+
+func (x Type) String() string {
+	return proto.EnumName(Type_name, int32(x))
+}
+func (Type) EnumDescriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+type Ref struct {
+	Version int64     `protobuf:"varint,1,opt,name=version" json:"version,omitempty"`
+	From    *Location `protobuf:"bytes,2,opt,name=from" json:"from,omitempty"`
+	To      *Location `protobuf:"bytes,3,opt,name=to" json:"to,omitempty"`
+	Type    Type      `protobuf:"varint,4,opt,name=type,enum=goref.proto.Type" json:"type,omitempty"`
+}
+
+func (m *Ref) Reset()                    { *m = Ref{} }
+func (m *Ref) String() string            { return proto.CompactTextString(m) }
+func (*Ref) ProtoMessage()               {}
+func (*Ref) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }
+
+func (m *Ref) GetVersion() int64 {
+	if m != nil {
+		return m.Version
+	}
+	return 0
+}
+
+func (m *Ref) GetFrom() *Location {
+	if m != nil {
+		return m.From
+	}
+	return nil
+}
+
+func (m *Ref) GetTo() *Location {
+	if m != nil {
+		return m.To
+	}
+	return nil
+}
+
+func (m *Ref) GetType() Type {
+	if m != nil {
+		return m.Type
+	}
+	return Type_Instantiation
+}
+
+type Location struct {
+	Position *Position `protobuf:"bytes,1,opt,name=position" json:"position,omitempty"`
+	Package  string    `protobuf:"bytes,2,opt,name=package" json:"package,omitempty"`
+	Ident    string    `protobuf:"bytes,3,opt,name=ident" json:"ident,omitempty"`
+}
+
+func (m *Location) Reset()                    { *m = Location{} }
+func (m *Location) String() string            { return proto.CompactTextString(m) }
+func (*Location) ProtoMessage()               {}
+func (*Location) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{1} }
+
+func (m *Location) GetPosition() *Position {
+	if m != nil {
+		return m.Position
+	}
+	return nil
+}
+
+func (m *Location) GetPackage() string {
+	if m != nil {
+		return m.Package
+	}
+	return ""
+}
+
+func (m *Location) GetIdent() string {
+	if m != nil {
+		return m.Ident
+	}
+	return ""
+}
+
+type Position struct {
+	Filename  string `protobuf:"bytes,1,opt,name=filename" json:"filename,omitempty"`
+	StartLine int32  `protobuf:"varint,2,opt,name=start_line,json=startLine" json:"start_line,omitempty"`
+	StartCol  int32  `protobuf:"varint,3,opt,name=start_col,json=startCol" json:"start_col,omitempty"`
+	EndLine   int32  `protobuf:"varint,4,opt,name=end_line,json=endLine" json:"end_line,omitempty"`
+	EndCol    int32  `protobuf:"varint,5,opt,name=end_col,json=endCol" json:"end_col,omitempty"`
+}
+
+func (m *Position) Reset()                    { *m = Position{} }
+func (m *Position) String() string            { return proto.CompactTextString(m) }
+func (*Position) ProtoMessage()               {}
+func (*Position) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{2} }
+
+func (m *Position) GetFilename() string {
+	if m != nil {
+		return m.Filename
+	}
+	return ""
+}
+
+func (m *Position) GetStartLine() int32 {
+	if m != nil {
+		return m.StartLine
+	}
+	return 0
+}
+
+func (m *Position) GetStartCol() int32 {
+	if m != nil {
+		return m.StartCol
+	}
+	return 0
+}
+
+func (m *Position) GetEndLine() int32 {
+	if m != nil {
+		return m.EndLine
+	}
+	return 0
+}
+
+func (m *Position) GetEndCol() int32 {
+	if m != nil {
+		return m.EndCol
+	}
+	return 0
+}
+
+func init() {
+	proto.RegisterType((*Ref)(nil), "goref.proto.Ref")
+	proto.RegisterType((*Location)(nil), "goref.proto.Location")
+	proto.RegisterType((*Position)(nil), "goref.proto.Position")
+	proto.RegisterEnum("goref.proto.Type", Type_name, Type_value)
+}
+
+func init() { proto.RegisterFile("ref.proto", fileDescriptor0) }
+
+var fileDescriptor0 = []byte{
+	// 347 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0x7c, 0x91, 0x4f, 0x4b, 0xf3, 0x40,
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+	0x67, 0xc1, 0x5f, 0x46, 0xdf, 0x6a, 0x5c, 0x40, 0x68, 0x8f, 0x35, 0x65, 0xe1, 0xcc, 0x5b, 0x4e,
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+	0x2a, 0x38, 0x85, 0xf1, 0x56, 0x35, 0x96, 0x2b, 0x2b, 0xdc, 0x51, 0xd2, 0x7f, 0x18, 0x43, 0xb8,
+	0xe1, 0x52, 0xa6, 0x1e, 0x22, 0x4c, 0xb6, 0x55, 0x2d, 0xa9, 0x22, 0x65, 0x3b, 0xea, 0xe3, 0x18,
+	0x92, 0x87, 0x37, 0x4b, 0xaa, 0x7d, 0xc6, 0x34, 0x40, 0x80, 0xc1, 0xb6, 0xaa, 0xb5, 0xb1, 0x69,
+	0xd8, 0x22, 0x46, 0x25, 0x19, 0x52, 0x39, 0xa5, 0xd1, 0xf3, 0xc0, 0x5d, 0xf1, 0xfe, 0x33, 0x00,
+	0x00, 0xff, 0xff, 0x6d, 0xca, 0x56, 0x68, 0x26, 0x02, 0x00, 0x00,
+}
diff --git a/proto/ref.proto b/proto/ref.proto
new file mode 100644
index 0000000..905efbb
--- /dev/null
+++ b/proto/ref.proto
@@ -0,0 +1,33 @@
+syntax = "proto3";
+
+package goref.proto;
+
+message Ref {
+  int64 version = 1;
+  Location from = 2;
+  Location to = 3;
+  Type type = 4;
+}
+
+message Location {
+  Position position = 1;
+  string package = 2;
+  string ident = 3;
+}
+
+message Position {
+  string filename = 1;
+  int32 start_line = 2;
+  int32 start_col = 3;
+  int32 end_line = 4;
+  int32 end_col = 5;
+}
+
+enum Type {
+  Instantiation = 0;
+  Call = 1;
+  Implementation = 2;
+  Extension = 3;
+  Import = 4;
+  Reference = 5;
+}