diff --git a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/FormatExtension.java b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/FormatExtension.java
new file mode 100644
index 000000000..8b22d8c6e
--- /dev/null
+++ b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/FormatExtension.java
@@ -0,0 +1,93 @@
+/*
+ * @(#)FormatExtension.java
+ *
+ * Copyright (c) 2025 The authors and contributors of JHotDraw.
+ * You may not use, copy or modify this file, except in compliance with the
+ * accompanying license terms.
+ */
+package org.jhotdraw.draw.io;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+public final class FormatExtension {
+
+    private final String extension;
+
+    /**
+     * Creates a new format extension.
+     *
+     * @param extension the file extension (without leading dot)
+     * @throws IllegalArgumentException if extension is null or empty
+     */
+    public FormatExtension(String extension) {
+        if (extension == null || extension.trim().isEmpty()) {
+            throw new IllegalArgumentException("Extension cannot be null or empty");
+        }
+        // Normalize to lowercase for consistent comparison
+        this.extension = extension.trim().toLowerCase();
+    }
+
+    /**
+     * Returns the normalized extension string.
+     *
+     * @return the extension in lowercase
+     */
+    public String getValue() {
+        return extension;
+    }
+
+    /**
+     * Checks if this extension matches the given string (case-insensitive).
+     *
+     * @param other the string to compare
+     * @return true if they match
+     */
+    public boolean matches(String other) {
+        if (other == null) {
+            return false;
+        }
+        return extension.equalsIgnoreCase(other.trim());
+    }
+
+    /**
+     * Creates a set of FormatExtension objects from an array of strings.
+     *
+     * @param extensions array of extension strings
+     * @return immutable set of FormatExtension objects
+     */
+    public static Set<FormatExtension> createSet(String... extensions) {
+        if (extensions == null || extensions.length == 0) {
+            return Collections.emptySet();
+        }
+        Set<FormatExtension> set = new HashSet<>();
+        for (String ext : extensions) {
+            if (ext != null && !ext.trim().isEmpty()) {
+                set.add(new FormatExtension(ext));
+            }
+        }
+        return Collections.unmodifiableSet(set);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        FormatExtension that = (FormatExtension) obj;
+        return extension.equals(that.extension);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(extension);
+    }
+
+    @Override
+    public String toString() {
+        return extension;
+    }
+}
+
diff --git a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatProvider.java b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatProvider.java
index e159358a7..58e289c6d 100644
--- a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatProvider.java
+++ b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatProvider.java
@@ -21,9 +21,6 @@
  *   <li>Register with {@link ImageFormatRegistry#registerProvider(ImageFormatProvider)}</li>
  *   <li>Or add to META-INF/services/org.jhotdraw.draw.io.ImageFormatProvider for SPI</li>
  * </ol>
- * 
- * @author JHotDraw
- * @version $Id$
  */
 public interface ImageFormatProvider {
     
diff --git a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatRegistry.java b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatRegistry.java
index 7a5ca9f7e..782642ef2 100644
--- a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatRegistry.java
+++ b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/ImageFormatRegistry.java
@@ -26,9 +26,6 @@
  * List&lt;InputFormat&gt; formats = ImageFormatRegistry.getInputFormats(myImageFigure);
  * drawing.getInputFormats().addAll(formats);
  * </pre>
- * 
- * @author JHotDraw
- * @version $Id$
  */
 public final class ImageFormatRegistry {
     
diff --git a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/JpegFormatProvider.java b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/JpegFormatProvider.java
index 894a77a4c..275950fd8 100644
--- a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/JpegFormatProvider.java
+++ b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/JpegFormatProvider.java
@@ -15,9 +15,6 @@
  * 
  * <p>JPEG uses lossy compression, making it ideal for photographs
  * and images with smooth color gradients. Supports both .jpg and .jpeg extensions.</p>
- * 
- * @author JHotDraw
- * @version $Id$
  */
 public class JpegFormatProvider implements ImageFormatProvider {
     
diff --git a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/PngFormatProvider.java b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/PngFormatProvider.java
index e5d0c23b7..828043c29 100644
--- a/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/PngFormatProvider.java
+++ b/jhotdraw-core/src/main/java/org/jhotdraw/draw/io/PngFormatProvider.java
@@ -15,9 +15,6 @@
  * 
  * <p>PNG supports lossless compression and transparency (alpha channel),
  * making it ideal for graphics with sharp edges or text.</p>
- * 
- * @author JHotDraw
- * @version $Id$
  */
 public class PngFormatProvider implements ImageFormatProvider {
     
diff --git a/jhotdraw-core/src/test/java/org/jhotdraw/draw/figure/RectangleFigureTest.java b/jhotdraw-core/src/test/java/org/jhotdraw/draw/figure/RectangleFigureTest.java
index 1e2175e37..aae6219ba 100644
--- a/jhotdraw-core/src/test/java/org/jhotdraw/draw/figure/RectangleFigureTest.java
+++ b/jhotdraw-core/src/test/java/org/jhotdraw/draw/figure/RectangleFigureTest.java
@@ -32,8 +32,6 @@
 /**
  * Comprehensive unit tests for RectangleFigure using JUnit 4, AssertJ, and Mockito.
  * Tests focus on geometric operations, boundary conditions, and drawing behavior.
- *
- * @author JHotDraw Team
  */
 public class RectangleFigureTest {