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diff --git a/engine/src/core/checkers/quals/SubtypeOf.java b/engine/src/core/checkers/quals/SubtypeOf.java
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+++ b/engine/src/core/checkers/quals/SubtypeOf.java
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+package checkers.quals;
+
+import java.lang.annotation.*;
+
+/**
+ * A meta-annotation to specify all the qualifiers that the given qualifier
+ * is a subtype of.  This provides a declarative way to specify the type
+ * qualifier hierarchy.  (Alternatively, the hierarchy can be defined
+ * procedurally by subclassing {@link checkers.types.QualifierHierarchy} or
+ * {@link checkers.types.TypeHierarchy}.)
+ *
+ * <p>
+ * Example:
+ * <pre> @SubtypeOf( { Nullable.class } )
+ * public @interface NonNull { }
+ * </pre>
+ *
+ * <p>
+ *
+ * If a qualified type is a subtype of the same type without any qualifier,
+ * then use <code>Unqualified.class</code> in place of a type qualifier
+ * class.  For example, to express that <code>@Encrypted <em>C</em></code>
+ * is a subtype of <code><em>C</em></code> (for every class
+ * <code><em>C</em></code>), and likewise for <code>@Interned</code>, write:
+ *
+ * <pre> @SubtypeOf(Unqualified.class)
+ * public @interface Encrypted { }
+ *
+ * &#64;SubtypeOf(Unqualified.class)
+ * public @interface Interned { }
+ * </pre>
+ *
+ * <p>
+ *
+ * For the root type qualifier in the qualifier hierarchy (i.e., the
+ * qualifier that is a supertype of all other qualifiers in the given
+ * hierarchy), use an empty set of values:
+ *
+ * <pre> @SubtypeOf( { } )
+ * public @interface Nullable { }
+ *
+ * &#64;SubtypeOf( {} )
+ * public @interface ReadOnly { }
+ * </pre>
+ *
+ * <p>
+ * Together, all the @SubtypeOf meta-annotations fully describe the type
+ * qualifier hierarchy.
+ * No @SubtypeOf meta-annotation is needed on (or can be written on) the
+ * Unqualified pseudo-qualifier, whose position in the hierarchy is
+ * inferred from the meta-annotations on the explicit qualifiers.
+ */
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.ANNOTATION_TYPE)
+public @interface SubtypeOf {
+    /** An array of the supertype qualifiers of the annotated qualifier **/
+    Class<? extends Annotation>[] value();
+}