diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Components.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Components.java
index f0037480f..c1eeacd84 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Components.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Components.java
@@ -22,6 +22,7 @@
 import java.lang.annotation.Target;
 
 import org.eclipse.microprofile.openapi.annotations.callbacks.Callback;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.headers.Header;
 import org.eclipse.microprofile.openapi.annotations.links.Link;
 import org.eclipse.microprofile.openapi.annotations.media.ExampleObject;
@@ -105,4 +106,15 @@
      * @return the reusable Callback objects.
      */
     Callback[] callbacks() default {};
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.Components Components} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
+
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/ExternalDocumentation.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/ExternalDocumentation.java
index 6653cff13..6b1fff0cf 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/ExternalDocumentation.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/ExternalDocumentation.java
@@ -23,6 +23,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This annotation allows referencing an external resource for extended documentation.
  * <p>
@@ -56,4 +58,13 @@
      **/
     String url() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.ExternalDocumentation
+     * ExternalDocumentation} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/OpenAPIDefinition.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/OpenAPIDefinition.java
index 6b971ab90..a42dd9f47 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/OpenAPIDefinition.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/OpenAPIDefinition.java
@@ -23,6 +23,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.info.Info;
 import org.eclipse.microprofile.openapi.annotations.security.SecurityRequirement;
 import org.eclipse.microprofile.openapi.annotations.servers.Server;
@@ -87,4 +88,14 @@
      * @return the element with a set of reusable objects for different aspects of the OAS.
      */
     Components components() default @Components;
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.OpenAPI OpenAPI} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Operation.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Operation.java
index 6fb327355..a3d8297f6 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Operation.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/Operation.java
@@ -23,6 +23,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * Describes a single API operation on a path.
  * 
@@ -75,4 +77,14 @@
      * @return whether or not this operation is hidden
      */
     boolean hidden() default false;
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.Operation Operation} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/Callback.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/Callback.java
index c77f03aa5..0a09d7cf7 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/Callback.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/Callback.java
@@ -24,6 +24,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This object represents a callback URL that will be invoked.
  * 
@@ -74,4 +76,14 @@
      * @return reference to a callback object definition
      **/
     String ref() default "";
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.callbacks.Callback Callback}
+     * model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/CallbackOperation.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/CallbackOperation.java
index 291ed01c3..376113c30 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/CallbackOperation.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/CallbackOperation.java
@@ -109,9 +109,12 @@
     SecurityRequirement[] security() default {};
 
     /**
-     * The list of optional extensions.
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.Operation Operation} model
+     * corresponding to the containing annotation.
      *
-     * @return an optional array of extensions
+     * @return array of extensions
+     * 
+     * @since 3.1
      */
     Extension[] extensions() default {};
 }
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/package-info.java
index 1044a066d..e405149b6 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/callbacks/package-info.java
@@ -44,6 +44,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.callbacks;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/extensions/Extension.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/extensions/Extension.java
index cd5016356..691ffd8ca 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/extensions/Extension.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/extensions/Extension.java
@@ -24,7 +24,51 @@
 import java.lang.annotation.Target;
 
 /**
- * A named extension that should be added to the OpenAPI definition.
+ * A named extension that should be added to the OpenAPI definition. The names of all extensions MUST begin with
+ * {@code x-} or else an invalid document will potentially be created.
+ * 
+ * <p>
+ * Although this annotation may currently be placed directly on a Java language element target, application developers
+ * should instead utilize the {@code extensions} property of the particular annotation that corresponds to the model
+ * being extended. Use of the annotation directly on a Java element is often ambiguous and it may result in the
+ * extension being added to an incorrect location in the OpenAPI model. Future releases of MicroProfile OpenAPI may
+ * remove the capability of placing this annotation directly on a Java element.
+ * 
+ * <p>
+ * When {@code @Extension} annotations are used both directly on a Java element as well as within another annotation
+ * that targets the same Java element, implementations will apply only the nested extensions to the resulting model.
+ * 
+ * <p>
+ * Example of <em>preferred</em> use with {@code @Extension} nested within an {@code @Schema} annotation:
+ * 
+ * <pre>
+ * class MyPojo {
+ *
+ *     {@literal @}Schema(
+ *         type = SchemaType.STRING,
+ *         extensions = {@literal @}Extension(
+ *             name = "x-custom-property",
+ *             value = "custom-value")
+ *     String property1;
+ * 
+ * }
+ * </pre>
+ * 
+ * <p>
+ * Example of <em>deprecated</em> use with {@code @Extension} placed directly on a field implied to be a schema
+ * property:
+ * 
+ * <pre>
+ * class MyPojo {
+ *
+ *     {@literal @}Extension(
+ *         name = "x-custom-property",
+ *         value = "custom-value")
+ *     String property1;
+ *
+ * }
+ * </pre>
+ * 
  */
 @Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE})
 @Retention(RetentionPolicy.RUNTIME)
@@ -32,9 +76,10 @@
 public @interface Extension {
 
     /**
-     * A name for the extension.
+     * A name for the extension. The names of all extensions MUST begin with {@code x-} or else an invalid document will
+     * potentially be created.
      *
-     * @return an option name for these extensions - will be prefixed with "x-"
+     * @return an option name for these extensions - must be prefixed with {@code x-}
      */
     String name();
 
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/Header.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/Header.java
index eb36e6687..c142c5524 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/Header.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/Header.java
@@ -22,6 +22,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.media.Schema;
 
 /**
@@ -92,4 +93,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.headers.Header Header} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/package-info.java
index bd0855c28..5a5af99d3 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/headers/package-info.java
@@ -26,6 +26,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.headers;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Contact.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Contact.java
index aa31e00c5..81bf1cf28 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Contact.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Contact.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * Contact information for the exposed API.
  * 
@@ -52,4 +54,13 @@
      **/
     String email() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.info.Contact Contact} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Info.java
index f3d280b03..e0fa5fafa 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/Info.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This annotation provides metadata about the API, and maps to the Info object in OpenAPI Specification 3.
  * 
@@ -73,4 +75,13 @@
      **/
     String version();
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.info.Info Info} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/License.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/License.java
index 71d75663e..7048c0642 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/License.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/License.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * License information for the exposed API.
  * 
@@ -45,4 +47,13 @@
      **/
     String url() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.info.License License} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/package-info.java
index b36d5ab2c..741338fe6 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/info/package-info.java
@@ -34,6 +34,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.info;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/Link.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/Link.java
index 4e52227d2..24c864b5f 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/Link.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/Link.java
@@ -22,6 +22,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.servers.Server;
 
 /**
@@ -103,4 +104,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.links.Link Link} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/package-info.java
index e0c769487..a768ee637 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/links/package-info.java
@@ -31,6 +31,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.links;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Content.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Content.java
index 71c799c1d..e46e899b5 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Content.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Content.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This object provides schema and examples for a particular media type.
  * 
@@ -72,4 +74,13 @@
      */
     Encoding[] encoding() default {};
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.media.MediaType MediaType}
+     * model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Encoding.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Encoding.java
index 1f52052e7..e7095514f 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Encoding.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Encoding.java
@@ -22,6 +22,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.headers.Header;
 
 /**
@@ -103,4 +104,13 @@
      */
     Header[] headers() default {};
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.media.Encoding Encoding}
+     * model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/ExampleObject.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/ExampleObject.java
index e902ec5fb..1197d3a4a 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/ExampleObject.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/ExampleObject.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This object illustrates an example of a particular content
  * 
@@ -91,4 +93,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.examples.Example Example}
+     * model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Schema.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Schema.java
index 13dee5f4d..54df22e22 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Schema.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/Schema.java
@@ -25,6 +25,7 @@
 
 import org.eclipse.microprofile.openapi.annotations.ExternalDocumentation;
 import org.eclipse.microprofile.openapi.annotations.enums.SchemaType;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 
 /**
  * The Schema Object allows the definition of input and output data types. These types can be objects, but also
@@ -399,4 +400,14 @@
      * @since 2.0
      */
     SchemaProperty[] properties() default {};
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.media.Schema Schema} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/SchemaProperty.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/SchemaProperty.java
index 1f962094d..33f5e9852 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/SchemaProperty.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/SchemaProperty.java
@@ -22,6 +22,7 @@
 
 import org.eclipse.microprofile.openapi.annotations.ExternalDocumentation;
 import org.eclipse.microprofile.openapi.annotations.enums.SchemaType;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 
 /**
  * The SchemaProperty Object allows the definition of input and output data types nested within the
@@ -362,4 +363,15 @@
      * @return whether the items in this array are unique
      **/
     boolean uniqueItems() default false;
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.media.Schema Schema} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
+
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/package-info.java
index 7a67836e6..e0495c13a 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/media/package-info.java
@@ -25,6 +25,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.1")
+@org.osgi.annotation.versioning.Version("1.2")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.media;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/package-info.java
index d02041969..27404b1c6 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/package-info.java
@@ -34,5 +34,5 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 package org.eclipse.microprofile.openapi.annotations;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/Parameter.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/Parameter.java
index 6ad39edd0..b20a96029 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/Parameter.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/Parameter.java
@@ -27,6 +27,7 @@
 import org.eclipse.microprofile.openapi.annotations.enums.Explode;
 import org.eclipse.microprofile.openapi.annotations.enums.ParameterIn;
 import org.eclipse.microprofile.openapi.annotations.enums.ParameterStyle;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.media.Content;
 import org.eclipse.microprofile.openapi.annotations.media.ExampleObject;
 import org.eclipse.microprofile.openapi.annotations.media.Schema;
@@ -206,4 +207,14 @@
      * @return reference to a parameter
      **/
     String ref() default "";
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.parameters.Parameter
+     * Parameter} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/RequestBody.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/RequestBody.java
index 0f17f2e5c..4c2f49d8c 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/RequestBody.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/RequestBody.java
@@ -23,6 +23,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.media.Content;
 
 /**
@@ -81,4 +82,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.parameters.RequestBody
+     * RequestBody} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/package-info.java
index 0363db867..ef05542d6 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/parameters/package-info.java
@@ -32,6 +32,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.1")
+@org.osgi.annotation.versioning.Version("1.2")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.parameters;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponse.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponse.java
index e7b2d8b77..c047a9360 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponse.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponse.java
@@ -24,6 +24,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 import org.eclipse.microprofile.openapi.annotations.headers.Header;
 import org.eclipse.microprofile.openapi.annotations.links.Link;
 import org.eclipse.microprofile.openapi.annotations.media.Content;
@@ -129,4 +130,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.responses.APIResponse
+     * APIResponse} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponses.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponses.java
index 21a218de6..d3dc34bc7 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponses.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/APIResponses.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * The ApiResponses annotation is a container for @ApiResponse annotations. When used on a method it is treated as if
  * each ApiResponse annotation were applied individually.
@@ -40,4 +42,13 @@
      **/
     APIResponse[] value() default {};
 
-}
\ No newline at end of file
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.responses.APIResponses
+     * APIResponses} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
+}
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/package-info.java
index 9b40274f6..e0a019d7e 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/responses/package-info.java
@@ -30,6 +30,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.1")
+@org.osgi.annotation.versioning.Version("1.2")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.responses;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlow.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlow.java
index 062812103..d54775220 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlow.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlow.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * Configuration details for a supported OAuth Flow.
  * 
@@ -74,4 +76,13 @@
      **/
     OAuthScope[] scopes() default {};
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.security.OAuthFlow
+     * OAuthFlow} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlows.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlows.java
index 407ee360a..44ba2fb7e 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlows.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/OAuthFlows.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * Allows configuration of the supported OAuth Flows.
  * 
@@ -60,4 +62,13 @@
      **/
     OAuthFlow authorizationCode() default @OAuthFlow();
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.security.OAuthFlows
+     * OAuthFlows} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/SecurityScheme.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/SecurityScheme.java
index 7e6efe051..6279f3fb3 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/SecurityScheme.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/SecurityScheme.java
@@ -26,6 +26,7 @@
 
 import org.eclipse.microprofile.openapi.annotations.enums.SecuritySchemeIn;
 import org.eclipse.microprofile.openapi.annotations.enums.SecuritySchemeType;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 
 /**
  * Defines a security scheme that can be used by the operations. Supported schemes are HTTP authentication, an API key
@@ -137,4 +138,13 @@
      **/
     String ref() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.security.SecurityScheme
+     * SecurityScheme} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/package-info.java
index 7b96f0169..27ed594f2 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/security/package-info.java
@@ -36,6 +36,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.security;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/Server.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/Server.java
index 9581135e2..4113dd529 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/Server.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/Server.java
@@ -24,6 +24,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * This annotation represents a Server used in an operation or used by all operations in an OpenAPI document.
  * <p>
@@ -72,4 +74,13 @@
      **/
     ServerVariable[] variables() default {};
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.servers.Server Server} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/ServerVariable.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/ServerVariable.java
index b63b85b22..1702d6f83 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/ServerVariable.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/ServerVariable.java
@@ -22,6 +22,8 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
+
 /**
  * An object representing a Server Variable for server URL template substitution.
  * 
@@ -62,4 +64,13 @@
      **/
     String description() default "";
 
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.servers.ServerVariable
+     * ServerVariable} model corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/package-info.java
index 6a6e5ccfb..1dba8cbbd 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/servers/package-info.java
@@ -28,6 +28,6 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 @org.osgi.annotation.versioning.ProviderType
 package org.eclipse.microprofile.openapi.annotations.servers;
\ No newline at end of file
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/Tag.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/Tag.java
index 90376ec88..1a0bd3f85 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/Tag.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/Tag.java
@@ -25,6 +25,7 @@
 import java.lang.annotation.Target;
 
 import org.eclipse.microprofile.openapi.annotations.ExternalDocumentation;
+import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
 
 /**
  * This object represents a tag. A tag is meta-information you can use to help organize your API end-points and it can
@@ -107,4 +108,14 @@
      * @return reference to a tag
      **/
     String ref() default "";
+
+    /**
+     * List of extensions to be added to the {@link org.eclipse.microprofile.openapi.models.tags.Tag Tag} model
+     * corresponding to the containing annotation.
+     *
+     * @return array of extensions
+     * 
+     * @since 3.1
+     */
+    Extension[] extensions() default {};
 }
diff --git a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/package-info.java b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/package-info.java
index e28c46a91..6ab04f0ae 100644
--- a/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/package-info.java
+++ b/api/src/main/java/org/eclipse/microprofile/openapi/annotations/tags/package-info.java
@@ -35,5 +35,5 @@
  * </pre>
  */
 
-@org.osgi.annotation.versioning.Version("1.0")
+@org.osgi.annotation.versioning.Version("1.1")
 package org.eclipse.microprofile.openapi.annotations.tags;
\ No newline at end of file
diff --git a/tck/src/main/java/org/eclipse/microprofile/openapi/apps/petstore/resource/PetStoreResource.java b/tck/src/main/java/org/eclipse/microprofile/openapi/apps/petstore/resource/PetStoreResource.java
index 992d121d3..6a2779ba5 100644
--- a/tck/src/main/java/org/eclipse/microprofile/openapi/apps/petstore/resource/PetStoreResource.java
+++ b/tck/src/main/java/org/eclipse/microprofile/openapi/apps/petstore/resource/PetStoreResource.java
@@ -22,6 +22,7 @@
 import org.eclipse.microprofile.openapi.annotations.media.Schema;
 import org.eclipse.microprofile.openapi.annotations.parameters.Parameter;
 import org.eclipse.microprofile.openapi.annotations.responses.APIResponse;
+import org.eclipse.microprofile.openapi.annotations.responses.APIResponses;
 import org.eclipse.microprofile.openapi.annotations.security.SecurityRequirement;
 import org.eclipse.microprofile.openapi.annotations.security.SecurityRequirements;
 import org.eclipse.microprofile.openapi.annotations.security.SecurityScheme;
@@ -61,8 +62,13 @@ public class PetStoreResource {
     @GET
     @Path("/inventory")
     @Produces({"application/json", "application/xml"})
-    @APIResponse(responseCode = "200", description = "successful operation")
+    @APIResponses(extensions = @Extension(name = "x-responses-ext", value = "test-responses-ext"), value = {
+            @APIResponse(responseCode = "200", description = "successful operation", extensions = @Extension(name = "x-response-ext", value = "test-response-ext")),
+            @APIResponse(responseCode = "500", description = "server error", extensions = {}),
+            @APIResponse(responseCode = "503", description = "service not available", content = @Content(extensions = @Extension(name = "x-notavailable-ext", value = "true"))),
+    })
     @Operation(summary = "Returns pet inventories by status", description = "Returns a map of status codes to quantities")
+    @Extension(name = "x-operation-ext", value = "test-operation-ext")
     public java.util.Map<String, Integer> getInventory() {
         return petData.getInventoryByStatus();
     }
diff --git a/tck/src/main/java/org/eclipse/microprofile/openapi/tck/PetStoreAppTest.java b/tck/src/main/java/org/eclipse/microprofile/openapi/tck/PetStoreAppTest.java
index dceeb240e..5c0eecd58 100644
--- a/tck/src/main/java/org/eclipse/microprofile/openapi/tck/PetStoreAppTest.java
+++ b/tck/src/main/java/org/eclipse/microprofile/openapi/tck/PetStoreAppTest.java
@@ -24,6 +24,7 @@
 import static org.hamcrest.Matchers.hasItems;
 import static org.hamcrest.Matchers.hasKey;
 import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
 import static org.hamcrest.Matchers.startsWith;
@@ -303,4 +304,26 @@ public void testAPIResponseSchemaDefaultResponseCode(String type) {
                         hasEntry(equalTo("type"), equalTo("object")),
                         hasEntry(equalTo("properties"), notNullValue())));
     }
+
+    @RunAsClient
+    @Test(dataProvider = "formatProvider")
+    public void testExtensionPlacement(String type) {
+        ValidatableResponse vr = callEndpoint(type);
+
+        final String X_OPERATION_EXT = "x-operation-ext";
+        final String TEST_OPERATION_EXT = "test-operation-ext";
+        String opPath = "paths.'/store/inventory'.get";
+
+        vr.body(opPath, hasEntry(equalTo(X_OPERATION_EXT), equalTo(TEST_OPERATION_EXT)));
+
+        vr.body(opPath + ".responses", hasEntry(equalTo("x-responses-ext"), equalTo("test-responses-ext")));
+        vr.body(opPath + ".responses.'200'", not(hasKey(X_OPERATION_EXT)));
+        vr.body(opPath + ".responses.'200'", hasEntry(equalTo("x-response-ext"), equalTo("test-response-ext")));
+        vr.body(opPath + ".responses.'500'", not(hasKey(X_OPERATION_EXT)));
+        vr.body(opPath + ".responses.'503'", hasEntry(equalTo(X_OPERATION_EXT), equalTo(TEST_OPERATION_EXT)));
+        vr.body(opPath + ".responses.'503'.content.'application/json'",
+                hasEntry(equalTo("x-notavailable-ext"), equalTo("true")));
+        vr.body(opPath + ".responses.'503'.content.'application/xml'",
+                hasEntry(equalTo("x-notavailable-ext"), equalTo("true")));
+    }
 }