diff --git a/cmd/cue/cmd/get_go.go b/cmd/cue/cmd/get_go.go
index 6c0194d..03bb4df 100644
--- a/cmd/cue/cmd/get_go.go
+++ b/cmd/cue/cmd/get_go.go
@@ -910,7 +910,7 @@
 		if b, ok := x.Key().Underlying().(*types.Basic); !ok || b.Kind() != types.String {
 			panic(fmt.Sprintf("unsupported map key type %T", x.Key()))
 		}
-		fmt.Fprintf(e.w, "{ <_>: ")
+		fmt.Fprintf(e.w, "{ [string]: ")
 		e.printType(x.Elem())
 		fmt.Fprintf(e.w, " }")
 
diff --git a/cmd/cue/cmd/testdata/pkg/cuelang.org/go/cmd/cue/cmd/testdata/code/go/pkg1/file1_go_gen.cue b/cmd/cue/cmd/testdata/pkg/cuelang.org/go/cmd/cue/cmd/testdata/code/go/pkg1/file1_go_gen.cue
index 7f1869f..653f748 100644
--- a/cmd/cue/cmd/testdata/pkg/cuelang.org/go/cmd/cue/cmd/testdata/code/go/pkg1/file1_go_gen.cue
+++ b/cmd/cue/cmd/testdata/pkg/cuelang.org/go/cmd/cue/cmd/testdata/code/go/pkg1/file1_go_gen.cue
@@ -25,7 +25,7 @@
 	// Time is mapped to CUE's internal type.
 	Time:   time.Time
 	Barzer: p2.Barzer
-	Map: {<_>: null | CustomJSON} @go(,map[string]*CustomJSON)
+	Map: {[string]: null | CustomJSON} @go(,map[string]*CustomJSON)
 	Slice1: [...int] @go(,[]int)
 	Slice2: [...] @go(,[]interface{})
 	Slice3: null | [...] @go(,*[]json.Unmarshaler)
diff --git a/cmd/cue/cmd/testdata/script/vet_expr.txt b/cmd/cue/cmd/testdata/script/vet_expr.txt
index dabbe47..31fbfb4 100644
--- a/cmd/cue/cmd/testdata/script/vet_expr.txt
+++ b/cmd/cue/cmd/testdata/script/vet_expr.txt
@@ -11,7 +11,7 @@
     ./data.yaml:20:7
 -- vet.cue --
 File :: {
-	translations <_>: {
+	translations: [string]: {
     lang: string
     text: string
   }
diff --git a/cmd/cue/cmd/testdata/script/vet_file.txt b/cmd/cue/cmd/testdata/script/vet_file.txt
index 672192b..e1b7ff9 100644
--- a/cmd/cue/cmd/testdata/script/vet_file.txt
+++ b/cmd/cue/cmd/testdata/script/vet_file.txt
@@ -3,13 +3,13 @@
 
 -- expect-stderr --
 translations.hello.lang: incomplete value (string):
-    ./vet.cue:2:26
+    ./vet.cue:2:31
 translations.hello.lang: conflicting values false and string (mismatched types bool and string):
     ./data.yaml:13:11
-    ./vet.cue:2:26
+    ./vet.cue:2:31
 -- vet.cue --
 
-translations: <_>: lang: string
+translations: [string]: lang: string
 
 File :: {
 	translations: {...}
diff --git a/cue/resolve_test.go b/cue/resolve_test.go
index 4afa740..4f4d627 100644
--- a/cue/resolve_test.go
+++ b/cue/resolve_test.go
@@ -1250,19 +1250,19 @@
 		desc: "non-closed definition carries over closedness to enclosed template",
 		in: `
 		S :: {
-			<_>: { a: int }
+			[string]: { a: int }
 		}
 		a: S & {
 			v: { b: int }
 		}
 		Q :: {
-			<_>: { a: int } | { b: int }
+			[string]: { a: int } | { b: int }
 		}
 		b: Q & {
 			w: { c: int }
 		}
 		R :: {
-			<_>: [{ a: int }, { b: int }]
+			[string]: [{ a: int }, { b: int }]
 		}
 		c: R & {
 			w: [{ d: int }, ...]
diff --git a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/apps/v1beta1/types_go_gen.cue b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/apps/v1beta1/types_go_gen.cue
index fd4c052..3300e82 100644
--- a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/apps/v1beta1/types_go_gen.cue
+++ b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/apps/v1beta1/types_go_gen.cue
@@ -29,7 +29,7 @@
 
 	// label query over pods that should match the replicas count. More info: http://kubernetes.io/docs/user-guide/labels#label-selectors
 	// +optional
-	selector?: {<_>: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
+	selector?: {[string]: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
 
 	// label selector for pods that should match the replicas count. This is a serializated
 	// version of both map-based and more expressive set-based selectors. This is done to
@@ -355,7 +355,7 @@
 
 	// The annotations to be updated to a deployment
 	// +optional
-	updatedAnnotations?: {<_>: string} @go(UpdatedAnnotations,map[string]string) @protobuf(2,bytes,rep)
+	updatedAnnotations?: {[string]: string} @go(UpdatedAnnotations,map[string]string) @protobuf(2,bytes,rep)
 
 	// The config of this deployment rollback.
 	rollbackTo: RollbackConfig @go(RollbackTo) @protobuf(3,bytes,opt)
diff --git a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/core/v1/types_go_gen.cue b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/core/v1/types_go_gen.cue
index f9e8799..da9047c 100644
--- a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/core/v1/types_go_gen.cue
+++ b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/core/v1/types_go_gen.cue
@@ -1132,7 +1132,7 @@
 
 	// Optional: Extra command options if any.
 	// +optional
-	options?: {<_>: string} @go(Options,map[string]string) @protobuf(5,bytes,rep)
+	options?: {[string]: string} @go(Options,map[string]string) @protobuf(5,bytes,rep)
 }
 
 // FlexVolume represents a generic volume resource that is
@@ -1162,7 +1162,7 @@
 
 	// Optional: Extra command options if any.
 	// +optional
-	options?: {<_>: string} @go(Options,map[string]string) @protobuf(5,bytes,rep)
+	options?: {[string]: string} @go(Options,map[string]string) @protobuf(5,bytes,rep)
 }
 
 // Represents a Persistent Disk resource in AWS.
@@ -1903,7 +1903,7 @@
 
 	// Attributes of the volume to publish.
 	// +optional
-	volumeAttributes?: {<_>: string} @go(VolumeAttributes,map[string]string) @protobuf(5,bytes,rep)
+	volumeAttributes?: {[string]: string} @go(VolumeAttributes,map[string]string) @protobuf(5,bytes,rep)
 
 	// ControllerPublishSecretRef is a reference to the secret object containing
 	// sensitive information to pass to the CSI driver to complete the CSI
@@ -1959,7 +1959,7 @@
 	// VolumeAttributes stores driver-specific properties that are passed to the CSI
 	// driver. Consult your driver's documentation for supported values.
 	// +optional
-	volumeAttributes?: {<_>: string} @go(VolumeAttributes,map[string]string) @protobuf(4,bytes,rep)
+	volumeAttributes?: {[string]: string} @go(VolumeAttributes,map[string]string) @protobuf(4,bytes,rep)
 
 	// NodePublishSecretRef is a reference to the secret object containing
 	// sensitive information to pass to the CSI driver to complete the CSI
@@ -3244,7 +3244,7 @@
 	// Selector which must match a node's labels for the pod to be scheduled on that node.
 	// More info: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/
 	// +optional
-	nodeSelector?: {<_>: string} @go(NodeSelector,map[string]string) @protobuf(7,bytes,rep)
+	nodeSelector?: {[string]: string} @go(NodeSelector,map[string]string) @protobuf(7,bytes,rep)
 
 	// ServiceAccountName is the name of the ServiceAccount to use to run this pod.
 	// More info: https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/
@@ -4006,7 +4006,7 @@
 	// controller, if empty defaulted to labels on Pod template.
 	// More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
 	// +optional
-	selector?: {<_>: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
+	selector?: {[string]: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
 
 	// Template is the object that describes the pod that will be created if
 	// insufficient replicas are detected. This takes precedence over a TemplateRef.
@@ -4247,7 +4247,7 @@
 	// Ignored if type is ExternalName.
 	// More info: https://kubernetes.io/docs/concepts/services-networking/service/
 	// +optional
-	selector?: {<_>: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
+	selector?: {[string]: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
 
 	// clusterIP is the IP address of the service and is usually assigned
 	// randomly by the master. If an address is specified manually and is not in
@@ -5020,7 +5020,7 @@
 ResourceAttachableVolumesPrefix :: "attachable-volumes-"
 
 // ResourceList is a set of (resource name, quantity) pairs.
-ResourceList :: {<_>: resource.Quantity}
+ResourceList :: {[string]: resource.Quantity}
 
 // Node is a worker node in Kubernetes.
 // Each node will have a unique identifier in the cache (i.e. in etcd).
@@ -5871,7 +5871,7 @@
 	// base64 encoded string, representing the arbitrary (possibly non-string)
 	// data value here. Described in https://tools.ietf.org/html/rfc4648#section-4
 	// +optional
-	data?: {<_>: bytes} @go(Data,map[string][]byte) @protobuf(2,bytes,rep)
+	data?: {[string]: bytes} @go(Data,map[string][]byte) @protobuf(2,bytes,rep)
 
 	// stringData allows specifying non-binary secret data in string form.
 	// It is provided as a write-only convenience method.
@@ -5879,7 +5879,7 @@
 	// It is never output when reading from the API.
 	// +k8s:conversion-gen=false
 	// +optional
-	stringData?: {<_>: string} @go(StringData,map[string]string) @protobuf(4,bytes,rep)
+	stringData?: {[string]: string} @go(StringData,map[string]string) @protobuf(4,bytes,rep)
 
 	// Used to facilitate programmatic handling of secret data.
 	// +optional
@@ -6019,7 +6019,7 @@
 	// The keys stored in Data must not overlap with the keys in
 	// the BinaryData field, this is enforced during validation process.
 	// +optional
-	data?: {<_>: string} @go(Data,map[string]string) @protobuf(2,bytes,rep)
+	data?: {[string]: string} @go(Data,map[string]string) @protobuf(2,bytes,rep)
 
 	// BinaryData contains the binary data.
 	// Each key must consist of alphanumeric characters, '-', '_' or '.'.
@@ -6029,7 +6029,7 @@
 	// Using this field will require 1.10+ apiserver and
 	// kubelet.
 	// +optional
-	binaryData?: {<_>: bytes} @go(BinaryData,map[string][]byte) @protobuf(3,bytes,rep)
+	binaryData?: {[string]: bytes} @go(BinaryData,map[string][]byte) @protobuf(3,bytes,rep)
 }
 
 // ConfigMapList is a resource containing a list of ConfigMap objects.
diff --git a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/extensions/v1beta1/types_go_gen.cue b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/extensions/v1beta1/types_go_gen.cue
index 71be27c..0e1b5a3 100644
--- a/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/extensions/v1beta1/types_go_gen.cue
+++ b/doc/tutorial/kubernetes/quick/pkg/k8s.io/api/extensions/v1beta1/types_go_gen.cue
@@ -24,7 +24,7 @@
 
 	// label query over pods that should match the replicas count. More info: http://kubernetes.io/docs/user-guide/labels#label-selectors
 	// +optional
-	selector?: {<_>: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
+	selector?: {[string]: string} @go(Selector,map[string]string) @protobuf(2,bytes,rep)
 
 	// label selector for pods that should match the replicas count. This is a serializated
 	// version of both map-based and more expressive set-based selectors. This is done to
@@ -140,7 +140,7 @@
 
 	// The annotations to be updated to a deployment
 	// +optional
-	updatedAnnotations?: {<_>: string} @go(UpdatedAnnotations,map[string]string) @protobuf(2,bytes,rep)
+	updatedAnnotations?: {[string]: string} @go(UpdatedAnnotations,map[string]string) @protobuf(2,bytes,rep)
 
 	// The config of this deployment rollback.
 	rollbackTo: RollbackConfig @go(RollbackTo) @protobuf(3,bytes,opt)
diff --git a/doc/tutorial/kubernetes/quick/pkg/k8s.io/apimachinery/pkg/apis/meta/v1/types_go_gen.cue b/doc/tutorial/kubernetes/quick/pkg/k8s.io/apimachinery/pkg/apis/meta/v1/types_go_gen.cue
index 9881cfa..9632b2b 100644
--- a/doc/tutorial/kubernetes/quick/pkg/k8s.io/apimachinery/pkg/apis/meta/v1/types_go_gen.cue
+++ b/doc/tutorial/kubernetes/quick/pkg/k8s.io/apimachinery/pkg/apis/meta/v1/types_go_gen.cue
@@ -210,14 +210,14 @@
 	// and services.
 	// More info: http://kubernetes.io/docs/user-guide/labels
 	// +optional
-	labels?: {<_>: string} @go(Labels,map[string]string) @protobuf(11,bytes,rep)
+	labels?: {[string]: string} @go(Labels,map[string]string) @protobuf(11,bytes,rep)
 
 	// Annotations is an unstructured key value map stored with a resource that may be
 	// set by external tools to store and retrieve arbitrary metadata. They are not
 	// queryable and should be preserved when modifying objects.
 	// More info: http://kubernetes.io/docs/user-guide/annotations
 	// +optional
-	annotations?: {<_>: string} @go(Annotations,map[string]string) @protobuf(12,bytes,rep)
+	annotations?: {[string]: string} @go(Annotations,map[string]string) @protobuf(12,bytes,rep)
 
 	// List of objects depended by this object. If ALL objects in the list have
 	// been deleted, this object will be garbage collected. If this object is managed by a controller,
@@ -1065,7 +1065,7 @@
 	// map is equivalent to an element of matchExpressions, whose key field is "key", the
 	// operator is "In", and the values array contains only "value". The requirements are ANDed.
 	// +optional
-	matchLabels?: {<_>: string} @go(MatchLabels,map[string]string) @protobuf(1,bytes,rep)
+	matchLabels?: {[string]: string} @go(MatchLabels,map[string]string) @protobuf(1,bytes,rep)
 
 	// matchExpressions is a list of label selector requirements. The requirements are ANDed.
 	// +optional
diff --git a/encoding/openapi/testdata/structural.cue b/encoding/openapi/testdata/structural.cue
index f1bb1c6..099fad7 100644
--- a/encoding/openapi/testdata/structural.cue
+++ b/encoding/openapi/testdata/structural.cue
@@ -3,7 +3,7 @@
 Attributes: {
 	//  A map of attribute name to its value.
 	attributes: {
-		<_>: AttrValue
+		[string]: AttrValue
 	}
 }
 
@@ -39,6 +39,6 @@
 Attributes_StringMap: {
 	//  Holds a set of name/value pairs.
 	entries: {
-		<_>: string
+		[string]: string
 	} @protobuf(1,type=map<string,string>)
 }
diff --git a/encoding/protobuf/examples_test.go b/encoding/protobuf/examples_test.go
index 7ce0ffa..5d7a7c8 100644
--- a/encoding/protobuf/examples_test.go
+++ b/encoding/protobuf/examples_test.go
@@ -53,7 +53,7 @@
 	// 	method?: [...string] @protobuf(2)
 	// 	method?: [...=~"^[A-Z]"]
 	// 	exmapleMap?: {
-	// 		<_>: string
+	// 		[string]: string
 	// 	} @protobuf(3,type=map<string,string>,exmaple_map)
 	// }
 }
diff --git a/encoding/protobuf/parse.go b/encoding/protobuf/parse.go
index e70601c..917f7fd 100644
--- a/encoding/protobuf/parse.go
+++ b/encoding/protobuf/parse.go
@@ -519,7 +519,7 @@
 
 		// All keys are converted to strings.
 		// TODO: support integer keys.
-		f.Label = &ast.TemplateLabel{Ident: ast.NewIdent("_")}
+		f.Label = ast.NewList(ast.NewIdent("string"))
 		f.Value = p.toExpr(x.Position, p.resolve(x.Position, x.Type, x.Options))
 
 		name := p.ident(x.Position, x.Name)
diff --git a/encoding/protobuf/testdata/attributes.proto.out.cue b/encoding/protobuf/testdata/attributes.proto.out.cue
index 936a6db..319e791 100644
--- a/encoding/protobuf/testdata/attributes.proto.out.cue
+++ b/encoding/protobuf/testdata/attributes.proto.out.cue
@@ -49,7 +49,7 @@
 Attributes: {
 	// A map of attribute name to its value.
 	attributes?: {
-		<_>: Attributes_AttributeValue
+		[string]: Attributes_AttributeValue
 	} @protobuf(1,type=map<string,AttributeValue>)
 }
 
@@ -91,7 +91,7 @@
 Attributes_StringMap: {
 	// Holds a set of name/value pairs.
 	entries?: {
-		<_>: string
+		[string]: string
 	} @protobuf(1,type=map<string,string>)
 }
 
@@ -108,42 +108,42 @@
 
 	// Holds attributes of type STRING, DNS_NAME, EMAIL_ADDRESS, URI
 	strings?: {
-		<_>: int32
+		[string]: int32
 	} @protobuf(2,type=map<sint32,sint32>)
 
 	// Holds attributes of type INT64
 	int64s?: {
-		<_>: int64
+		[string]: int64
 	} @protobuf(3,type=map<sint32,int64>)
 
 	// Holds attributes of type DOUBLE
 	doubles?: {
-		<_>: float64
+		[string]: float64
 	} @protobuf(4,type=map<sint32,double>)
 
 	// Holds attributes of type BOOL
 	bools?: {
-		<_>: bool
+		[string]: bool
 	} @protobuf(5,type=map<sint32,bool>)
 
 	// Holds attributes of type TIMESTAMP
 	time?: {
-		<_>: _time_.Time
+		[string]: _time_.Time
 	} @protobuf(6,type=map<sint32,google.protobuf.Timestamp>,"(gogoproto.nullable)=false","(gogoproto.stdtime)")
 
 	// Holds attributes of type DURATION
 	durations?: {
-		<_>: _time_.Duration
+		[string]: _time_.Duration
 	} @protobuf(7,type=map<sint32,google.protobuf.Duration>,"(gogoproto.nullable)=false","(gogoproto.stdduration)")
 
 	// Holds attributes of type BYTES
 	bytes?: {
-		<_>: _bytes_
+		[string]: _bytes_
 	} @protobuf(8,type=map<sint32,bytes>)
 
 	// Holds attributes of type STRING_MAP
 	stringMaps?: {
-		<_>: StringMap
+		[string]: StringMap
 	} @protobuf(9,type=map<sint32,StringMap>,string_maps,"(gogoproto.nullable)=false")
 }
 _time_ = time
@@ -154,6 +154,6 @@
 StringMap: {
 	// Holds a set of name/value pairs.
 	entries?: {
-		<_>: int32
+		[string]: int32
 	} @protobuf(1,type=map<sint32,sint32>)
 }
diff --git a/encoding/protobuf/testdata/client_config.proto.out.cue b/encoding/protobuf/testdata/client_config.proto.out.cue
index b9c5c3a..c9088ed 100644
--- a/encoding/protobuf/testdata/client_config.proto.out.cue
+++ b/encoding/protobuf/testdata/client_config.proto.out.cue
@@ -144,7 +144,7 @@
 	// is used to support per-service configuration for cases where a
 	// mixerclient serves multiple services.
 	serviceConfigs?: {
-		<_>: ServiceConfig
+		[string]: ServiceConfig
 	} @protobuf(2,type=map<string,ServiceConfig>,service_configs)
 
 	// Default destination service name if none was specified in the
diff --git a/encoding/protobuf/testdata/gateway.proto.out.cue b/encoding/protobuf/testdata/gateway.proto.out.cue
index 1a7ed21..82b141b 100644
--- a/encoding/protobuf/testdata/gateway.proto.out.cue
+++ b/encoding/protobuf/testdata/gateway.proto.out.cue
@@ -214,7 +214,7 @@
 	// the resource is present. In other words, the Gateway resource must
 	// reside in the same namespace as the gateway workload instance.
 	selector?: {
-		<_>: string
+		[string]: string
 	} @protobuf(2,type=map<string,string>)
 	selector?: <name>: name
 }
diff --git a/encoding/protobuf/testdata/istio.io/api/mixer/v1/attributes_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/mixer/v1/attributes_proto_gen.cue
index 27260d7..0918e35 100644
--- a/encoding/protobuf/testdata/istio.io/api/mixer/v1/attributes_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/mixer/v1/attributes_proto_gen.cue
@@ -49,7 +49,7 @@
 Attributes: {
 	// A map of attribute name to its value.
 	attributes?: {
-		<_>: Attributes_AttributeValue
+		[string]: Attributes_AttributeValue
 	} @protobuf(1,type=map<string,AttributeValue>)
 }
 
@@ -91,7 +91,7 @@
 Attributes_StringMap: {
 	// Holds a set of name/value pairs.
 	entries?: {
-		<_>: string
+		[string]: string
 	} @protobuf(1,type=map<string,string>)
 }
 
@@ -108,42 +108,42 @@
 
 	// Holds attributes of type STRING, DNS_NAME, EMAIL_ADDRESS, URI
 	strings?: {
-		<_>: int32
+		[string]: int32
 	} @protobuf(2,type=map<sint32,sint32>)
 
 	// Holds attributes of type INT64
 	int64s?: {
-		<_>: int64
+		[string]: int64
 	} @protobuf(3,type=map<sint32,int64>)
 
 	// Holds attributes of type DOUBLE
 	doubles?: {
-		<_>: float64
+		[string]: float64
 	} @protobuf(4,type=map<sint32,double>)
 
 	// Holds attributes of type BOOL
 	bools?: {
-		<_>: bool
+		[string]: bool
 	} @protobuf(5,type=map<sint32,bool>)
 
 	// Holds attributes of type TIMESTAMP
 	time?: {
-		<_>: _time_.Time
+		[string]: _time_.Time
 	} @protobuf(6,type=map<sint32,google.protobuf.Timestamp>,"(gogoproto.nullable)=false","(gogoproto.stdtime)")
 
 	// Holds attributes of type DURATION
 	durations?: {
-		<_>: _time_.Duration
+		[string]: _time_.Duration
 	} @protobuf(7,type=map<sint32,google.protobuf.Duration>,"(gogoproto.nullable)=false","(gogoproto.stdduration)")
 
 	// Holds attributes of type BYTES
 	bytes?: {
-		<_>: _bytes_
+		[string]: _bytes_
 	} @protobuf(8,type=map<sint32,bytes>)
 
 	// Holds attributes of type STRING_MAP
 	stringMaps?: {
-		<_>: StringMap
+		[string]: StringMap
 	} @protobuf(9,type=map<sint32,StringMap>,string_maps,"(gogoproto.nullable)=false")
 }
 _time_ = time
@@ -154,6 +154,6 @@
 StringMap: {
 	// Holds a set of name/value pairs.
 	entries?: {
-		<_>: int32
+		[string]: int32
 	} @protobuf(1,type=map<sint32,sint32>)
 }
diff --git a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/client_config_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/client_config_proto_gen.cue
index 4762234..0a561d6 100644
--- a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/client_config_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/client_config_proto_gen.cue
@@ -143,7 +143,7 @@
 	// is used to support per-service configuration for cases where a
 	// mixerclient serves multiple services.
 	serviceConfigs?: {
-		<_>: ServiceConfig
+		[string]: ServiceConfig
 	} @protobuf(2,type=map<string,ServiceConfig>,service_configs)
 
 	// Default destination service name if none was specified in the
diff --git a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/quota_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/quota_proto_gen.cue
index d94fe8e..c0203a6 100644
--- a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/quota_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/quota_proto_gen.cue
@@ -98,7 +98,7 @@
 	//     request.http_method:
 	//       exact: POST
 	clause?: {
-		<_>: StringMatch
+		[string]: StringMatch
 	} @protobuf(1,type=map<string,StringMatch>)
 }
 
diff --git a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/service_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/service_proto_gen.cue
index 1940810..d597c18 100644
--- a/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/service_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/mixer/v1/config/client/service_proto_gen.cue
@@ -43,6 +43,6 @@
 	// *Note:* When used for a VirtualService destination, labels MUST be empty.
 	//
 	labels?: {
-		<_>: string
+		[string]: string
 	} @protobuf(5,type=map<string,string>)
 }
diff --git a/encoding/protobuf/testdata/istio.io/api/mixer/v1/mixer_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/mixer/v1/mixer_proto_gen.cue
index b69bf68..d67f638 100644
--- a/encoding/protobuf/testdata/istio.io/api/mixer/v1/mixer_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/mixer/v1/mixer_proto_gen.cue
@@ -40,7 +40,7 @@
 
 	// The individual quotas to allocate
 	quotas?: {
-		<_>: CheckRequest_QuotaParams
+		[string]: CheckRequest_QuotaParams
 	} @protobuf(4,type=map<string,QuotaParams>,"(gogoproto.nullable)=false")
 }
 
@@ -60,7 +60,7 @@
 
 	// The resulting quota, one entry per requested quota.
 	quotas?: {
-		<_>: CheckResponse_QuotaResult
+		[string]: CheckResponse_QuotaResult
 	} @protobuf(3,type=map<string,QuotaResult>,"(gogoproto.nullable)=false")
 }
 
diff --git a/encoding/protobuf/testdata/istio.io/api/networking/v1alpha3/gateway_proto_gen.cue b/encoding/protobuf/testdata/istio.io/api/networking/v1alpha3/gateway_proto_gen.cue
index dd88b3e..1d301da 100644
--- a/encoding/protobuf/testdata/istio.io/api/networking/v1alpha3/gateway_proto_gen.cue
+++ b/encoding/protobuf/testdata/istio.io/api/networking/v1alpha3/gateway_proto_gen.cue
@@ -213,7 +213,7 @@
 	// the resource is present. In other words, the Gateway resource must
 	// reside in the same namespace as the gateway workload instance.
 	selector?: {
-		<_>: string
+		[string]: string
 	} @protobuf(2,type=map<string,string>)
 	selector?: {<name>: name}
 }