diff --git a/ets2panda/lexer/scripts/keywords.yaml b/ets2panda/lexer/scripts/keywords.yaml
index e437a74c86ef070257cd8999feac3d91b4d110e4..b00c4eba8706674b2cc85ec2edf9d4c38a32e2f4 100644
--- a/ets2panda/lexer/scripts/keywords.yaml
+++ b/ets2panda/lexer/scripts/keywords.yaml
@@ -64,7 +64,7 @@ keywords:
 
   - name: 'bigint'
     token: KEYW_BIGINT
-    keyword_like: [ts]
+    keyword_like: [ets, ts]
 
   - name: 'boolean'
     token: KEYW_BOOLEAN
@@ -317,7 +317,7 @@ keywords:
 
   - name: 'number'
     token: KEYW_NUMBER
-    keyword_like: [ts]
+    keyword_like: [ets, ts]
 
   - name: 'object'
     token: KEYW_OBJECT
@@ -390,7 +390,7 @@ keywords:
 
   - name: 'string'
     token: KEYW_STRING
-    keyword_like: [ts]
+    keyword_like: [ets, ts]
 
   - name: 'struct'
     token: KEYW_STRUCT
diff --git a/ets2panda/lexer/token/token.cpp b/ets2panda/lexer/token/token.cpp
index cf4e3e30337f97d6a3d3e715a0d097643d4ce638..6804f7f3bff32975330902134a6541b66a6fea1f 100644
--- a/ets2panda/lexer/token/token.cpp
+++ b/ets2panda/lexer/token/token.cpp
@@ -84,10 +84,7 @@ bool Token::IsReservedTypeName() const
         case TokenType::KEYW_ANY:
         case TokenType::KEYW_UNKNOWN:
         case TokenType::KEYW_NEVER:
-        case TokenType::KEYW_NUMBER:
-        case TokenType::KEYW_BIGINT:
         case TokenType::KEYW_BOOLEAN:
-        case TokenType::KEYW_STRING:
         case TokenType::KEYW_VOID:
         case TokenType::KEYW_OBJECT:
             return true;
@@ -107,6 +104,14 @@ bool Token::IsDefinableTypeName() const
         case TokenType::KEYW_INT:
         case TokenType::KEYW_CHAR:
         case TokenType::KEYW_LONG:
+        case TokenType::KEYW_UNDEFINED:
+        case TokenType::KEYW_VAR:
+        case TokenType::KEYW_IS:
+        case TokenType::KEYW_TYPEOF:
+        case TokenType::KEYW_YIELD:
+        case TokenType::KEYW_STRING:
+        case TokenType::KEYW_NUMBER:
+        case TokenType::KEYW_BIGINT:
             return true;
         default:
             return false;
diff --git a/ets2panda/test/parser/ets/user_defined_10-expected.txt b/ets2panda/test/parser/ets/user_defined_10-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..efd8c3d9e8e1827409709e6e7e77c0aebb9f053e
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_10-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_10.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_10.ets b/ets2panda/test/parser/ets/user_defined_10.ets
new file mode 100644
index 0000000000000000000000000000000000000000..f9e1cfaf294d917e73d17b6a94e5b91d4f71f0d0
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_10.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct number{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_11-expected.txt b/ets2panda/test/parser/ets/user_defined_11-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..ccb37342889137a61e91e1380cef40bc89b8663e
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_11-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_11.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_11.ets b/ets2panda/test/parser/ets/user_defined_11.ets
new file mode 100644
index 0000000000000000000000000000000000000000..81c6a8eba4fbc77a656bbce299100d03c182ec93
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_11.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class number{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_12-expected.txt b/ets2panda/test/parser/ets/user_defined_12-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..982182343689973849e5939078bd824b012b8de9
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_12-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_12.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_12.ets b/ets2panda/test/parser/ets/user_defined_12.ets
new file mode 100644
index 0000000000000000000000000000000000000000..ddf26139fea8c0a196e8dcfc18183342612f280f
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_12.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class yield{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_13-expected.txt b/ets2panda/test/parser/ets/user_defined_13-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..5f612f88730012121daabe8fe0d1f0069ada56da
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_13-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_13.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_13.ets b/ets2panda/test/parser/ets/user_defined_13.ets
new file mode 100644
index 0000000000000000000000000000000000000000..4a3731bd149279083248477e2ff41d5243087439
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_13.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class var{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_14-expected.txt b/ets2panda/test/parser/ets/user_defined_14-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..284028330d16a7664b4d73436610b57910e580b1
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_14-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_14.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_14.ets b/ets2panda/test/parser/ets/user_defined_14.ets
new file mode 100644
index 0000000000000000000000000000000000000000..0a029a471b85e0b84626d2b9b8140e4010411dda
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_14.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class typeof{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_15-expected.txt b/ets2panda/test/parser/ets/user_defined_15-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..7b9e0e15592a18eb9e7e9c8dcf8e313ba5d25624
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_15-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_15.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_15.ets b/ets2panda/test/parser/ets/user_defined_15.ets
new file mode 100644
index 0000000000000000000000000000000000000000..6cbc42525aa85bbb4eea4198a06e6288774ebc4f
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_15.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class is{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_16-expected.txt b/ets2panda/test/parser/ets/user_defined_16-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..dc9ff85f0b4c747b25c6856c9d40584800fe4267
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_16-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_16.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_16.ets b/ets2panda/test/parser/ets/user_defined_16.ets
new file mode 100644
index 0000000000000000000000000000000000000000..7c8941f3c1ef26eec24b3bfec9b732e2b79193ad
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_16.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct is{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_17-expected.txt b/ets2panda/test/parser/ets/user_defined_17-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..df6fbce58c223b46909dd20d1da33f03291eb95e
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_17-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_17.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_17.ets b/ets2panda/test/parser/ets/user_defined_17.ets
new file mode 100644
index 0000000000000000000000000000000000000000..72768b9dd6b37cbf9deefd20acd8178bf633be3f
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_17.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct var{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_18-expected.txt b/ets2panda/test/parser/ets/user_defined_18-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..2c1b7e257d928a3e59ac3f6ce85502cb921802f4
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_18-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_18.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_18.ets b/ets2panda/test/parser/ets/user_defined_18.ets
new file mode 100644
index 0000000000000000000000000000000000000000..43394973d9eb1a1cff3050089c075c7693bd7848
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_18.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct yield{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_19-expected.txt b/ets2panda/test/parser/ets/user_defined_19-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..9ccabf77dc7cd4ab6975ecf6bfa6304b28d92267
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_19-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_19.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_19.ets b/ets2panda/test/parser/ets/user_defined_19.ets
new file mode 100644
index 0000000000000000000000000000000000000000..764039bc9c734137a69e7c5f5824796fe3e73048
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_19.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct typeof{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_20-expected.txt b/ets2panda/test/parser/ets/user_defined_20-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..4b63249df42de83afb9e4b6c83affa5d14923be8
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_20-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_20.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_20.ets b/ets2panda/test/parser/ets/user_defined_20.ets
new file mode 100644
index 0000000000000000000000000000000000000000..602a2bbcd8de8a9c9f08ef4a1112748bab1bfb74
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_20.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct bigint{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_21-expected.txt b/ets2panda/test/parser/ets/user_defined_21-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..0b71c4d3a4617a64642c04101b3524c1f75da4e8
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_21-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_21.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_21.ets b/ets2panda/test/parser/ets/user_defined_21.ets
new file mode 100644
index 0000000000000000000000000000000000000000..eb13f23e66f3ac7127f20a46bb3058ae3d4468a6
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_21.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class bigint{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_8-expected.txt b/ets2panda/test/parser/ets/user_defined_8-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..c5113c1b0c575621bf34f9d4c25ab894d1bedc3f
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_8-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_8.ets:16:8]
diff --git a/ets2panda/test/parser/ets/user_defined_8.ets b/ets2panda/test/parser/ets/user_defined_8.ets
new file mode 100644
index 0000000000000000000000000000000000000000..49550fffd7788b7206d4c412b22ec665e15063da
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_8.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+struct string{
+  a : string = "15";
+}
diff --git a/ets2panda/test/parser/ets/user_defined_9-expected.txt b/ets2panda/test/parser/ets/user_defined_9-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..a89aa4ff1942b52beadb2749065bf0c0f048d443
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_9-expected.txt
@@ -0,0 +1 @@
+SyntaxError: Cannot be used as user-defined type. [user_defined_9.ets:16:7]
diff --git a/ets2panda/test/parser/ets/user_defined_9.ets b/ets2panda/test/parser/ets/user_defined_9.ets
new file mode 100644
index 0000000000000000000000000000000000000000..7ccd121781a84b5c1888a46e12fd28e972562679
--- /dev/null
+++ b/ets2panda/test/parser/ets/user_defined_9.ets
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class string{
+  a : string = "15";
+}