diff --git a/Sources/CoreXLSX/Relationships.swift b/Sources/CoreXLSX/Relationships.swift
index 99efa2fe..e3add651 100644
--- a/Sources/CoreXLSX/Relationships.swift
+++ b/Sources/CoreXLSX/Relationships.swift
@@ -130,13 +130,29 @@ public struct Relationship: Codable, Equatable {
       """
       http://purl.oclc.org/ooxml/officeDocument/relationships/extendedProperties
       """
+    case sheetMetadata =
+      """
+      http://schemas.openxmlformats.org/officeDocument/2006/relationships/\
+      sheetMetadata
+      """
+  }
+
+  enum CodingKeys: String, CodingKey {
+    case id
+    case rawType = "type"
+    case target
   }
 
   /// The identifier for this entity.
   public let id: String
 
   /// The type of this entity.
-  public let type: SchemaType
+  public var type: SchemaType? { SchemaType(rawValue: rawType) }
+
+  /// The raw type string.
+  /// This is needed so that Relationship decodes when encountering type strings
+  /// that are missing SchemaType cases.
+  public let rawType: String
 
   /// The path to this entity in the `.xlsx` archive.
   public let target: String