diff --git a/src/main/java/org/verapdf/as/ASAtom.java b/src/main/java/org/verapdf/as/ASAtom.java
index 89122324..a57b889e 100644
--- a/src/main/java/org/verapdf/as/ASAtom.java
+++ b/src/main/java/org/verapdf/as/ASAtom.java
@@ -134,6 +134,7 @@ public class ASAtom implements Comparable<ASAtom> {
     public static final ASAtom CID_TO_GID_MAP = new ASAtom("CIDToGIDMap");
     public static final ASAtom CID_SET = new ASAtom("CIDSet");
     public static final ASAtom CID_SYSTEM_INFO = new ASAtom("CIDSystemInfo");
+    public static final ASAtom CLASS_MAP = new ASAtom("ClassMap");
     public static final ASAtom CLR_F = new ASAtom("ClrF");
     public static final ASAtom CLR_FF = new ASAtom("ClrFf");
     public static final ASAtom CMAP = new ASAtom("CMap");
diff --git a/src/main/java/org/verapdf/pd/structure/PDStructTreeRoot.java b/src/main/java/org/verapdf/pd/structure/PDStructTreeRoot.java
index 9b501417..46519a5a 100644
--- a/src/main/java/org/verapdf/pd/structure/PDStructTreeRoot.java
+++ b/src/main/java/org/verapdf/pd/structure/PDStructTreeRoot.java
@@ -64,6 +64,10 @@ public Map<ASAtom, ASAtom> getRoleMap() {
 		return Collections.emptyMap();
 	}
 
+	public COSObject getClassMap() {
+		return getKey(ASAtom.CLASS_MAP);
+	}
+
 	public PDNumberTreeNode getParentTree() {
 		COSObject parentTree = getKey(ASAtom.PARENT_TREE);
 		if (parentTree != null && parentTree.getType().isDictionaryBased()) {
diff --git a/src/main/java/org/verapdf/tools/AttributeHelper.java b/src/main/java/org/verapdf/tools/AttributeHelper.java
index a5232b76..d333a770 100644
--- a/src/main/java/org/verapdf/tools/AttributeHelper.java
+++ b/src/main/java/org/verapdf/tools/AttributeHelper.java
@@ -4,6 +4,7 @@
 import org.verapdf.cos.COSArray;
 import org.verapdf.cos.COSObjType;
 import org.verapdf.cos.COSObject;
+import org.verapdf.pd.structure.PDStructTreeRoot;
 
 public class AttributeHelper {
 
@@ -67,21 +68,46 @@ private static Long getIntegerAttributeValue(org.verapdf.pd.PDObject simplePDObj
 	}
 
 	private static COSObject getAttributeValue(org.verapdf.pd.PDObject simplePDObject, ASAtom attributeName, String O,
+											   COSObjType type) {
+		COSObject attributeValue = getAttributeValue(simplePDObject.getKey(ASAtom.A), attributeName, O, type);
+		if (attributeValue == null) {
+			COSObject className = simplePDObject.getKey(ASAtom.C);
+			if (className != null) {
+				PDStructTreeRoot structTreeRoot = StaticResources.getDocument().getStructTreeRoot();
+				if (className.getType() == COSObjType.COS_NAME) {
+					attributeValue = getAttributeValue(structTreeRoot.getClassMap().getKey(className.getName()), 
+							attributeName, O, type);
+				} else if (className.getType() == COSObjType.COS_ARRAY) {
+					for (COSObject entry : (COSArray)className.getDirectBase()) {
+						if (entry != null && entry.getType() == COSObjType.COS_NAME) {
+							attributeValue = getAttributeValue(structTreeRoot.getClassMap().getKey(entry.getName()),
+									attributeName, O, type);
+							if (attributeValue != null) {
+								break;
+							}
+						}
+					}
+				}
+			}
+		}
+		return attributeValue != null ? attributeValue : COSObject.getEmpty();
+	}
+	
+	private static COSObject getAttributeValue(COSObject attributeObject, ASAtom attributeName, String O,
 	                                           COSObjType type) {
-		COSObject aValue = simplePDObject.getKey(ASAtom.A);
-		if (aValue == null) {
-			return COSObject.getEmpty();
+		if (attributeObject == null) {
+			return null;
 		}
-		if (aValue.getType() == COSObjType.COS_ARRAY) {
-			for (COSObject object : (COSArray) aValue.getDirectBase()) {
+		if (attributeObject.getType() == COSObjType.COS_ARRAY) {
+			for (COSObject object : (COSArray) attributeObject.getDirectBase()) {
 				COSObject value = getAttributeValue(object, attributeName, O);
 				if (value.getType() == type) {
 					return value;
 				}
 			}
 		}
-		COSObject value = getAttributeValue(aValue, attributeName, O);
-		return value.getType() == type ? value : COSObject.getEmpty();
+		COSObject value = getAttributeValue(attributeObject, attributeName, O);
+		return value.getType() == type ? value : null;
 	}
 
 	private static COSObject getAttributeValue(COSObject object, ASAtom attributeName, String O) {