diff --git a/current.txt b/current.txt
index 7af62c6..9c7151d 100644
--- a/current.txt
+++ b/current.txt
@@ -507,7 +507,7 @@
 92714960d1a53fc2ec557302b41c7cc93d2636d8364a44bd0f85be0c92927ff8 android.hardware.neuralnetworks@1.2::IExecutionCallback
 83885d366f22ada42c00d8854f0b7e7ba4cf73ddf80bb0d8e168ce132cec57ea android.hardware.neuralnetworks@1.2::IPreparedModel
 e1c734d1545e1a4ae749ff1dd9704a8e594c59aea7c8363159dc258e93e0df3b android.hardware.neuralnetworks@1.2::IPreparedModelCallback
-c752cff336d86762c26dc82e7e037f4962b815b1a068d2319d40a3d068e26f68 android.hardware.neuralnetworks@1.2::types
+447dda9186280d119e95937d707e8ae4729af9a922d22a29f069952da269c8c1 android.hardware.neuralnetworks@1.2::types
 cf7a4ba516a638f9b82a249c91fb603042c2d9ca43fd5aad9cf6c0401ed2a5d7 android.hardware.nfc@1.2::INfc
 abf98c2ae08bf765db54edc8068e36d52eb558cff6706b6fd7c18c65a1f3fc18 android.hardware.nfc@1.2::types
 4cb252dc6372a874aef666b92a6e9529915aa187521a700f0789065c3c702ead android.hardware.power.stats@1.0::IPowerStats
diff --git a/neuralnetworks/1.2/types.hal b/neuralnetworks/1.2/types.hal
index 4a8664f..bb5d777 100644
--- a/neuralnetworks/1.2/types.hal
+++ b/neuralnetworks/1.2/types.hal
@@ -4844,7 +4844,7 @@
         /**
          * The extension name.
          *
-         * See {@link Extension::name}.
+         * See {@link Extension::name} for the format specification.
          */
         string name;
 
@@ -5128,7 +5128,11 @@
     /**
      * The extension name.
      *
+     * The name must consist of lowercase latin letters, numbers, periods, and
+     * underscore signs. The name must contain at least one period.
+     *
      * The name must start with the reverse domain name of the vendor.
+     *
      * Example: com.google.test_extension
      */
     string name;
diff --git a/neuralnetworks/1.2/vts/functional/BasicTests.cpp b/neuralnetworks/1.2/vts/functional/BasicTests.cpp
index 2b88edd..365a750 100644
--- a/neuralnetworks/1.2/vts/functional/BasicTests.cpp
+++ b/neuralnetworks/1.2/vts/functional/BasicTests.cpp
@@ -64,7 +64,12 @@
                 for (auto& extension : extensions) {
                     std::string extensionName = extension.name;
                     EXPECT_FALSE(extensionName.empty());
-                    EXPECT_NE(extensionName.find("."), std::string::npos)
+                    for (char c : extensionName) {
+                        EXPECT_TRUE(('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' ||
+                                    c == '.')
+                                << "Extension name contains an illegal character: " << c;
+                    }
+                    EXPECT_NE(extensionName.find('.'), std::string::npos)
                             << "Extension name must start with the reverse domain name of the "
                                "vendor";
                 }