diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4dad916bf..e4f5c8210 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [2.18.0] 2022-xx-xx
+
+### Added
+- Added DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021 namespace
+- Added durableId attribute to DocumentFormat.OpenXml.Wordprocessing.NumberingPictureBullet
+
 ## [2.17.1] - 2022-06-28
 
 ### Removed
diff --git a/data/schemas/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json b/data/schemas/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json
new file mode 100644
index 000000000..befea875a
--- /dev/null
+++ b/data/schemas/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json
@@ -0,0 +1,100 @@
+{
+  "TargetNamespace": "http://schemas.microsoft.com/office/spreadsheetml/2021/extlinks2021",
+  "Types": [
+    {
+      "Name": "xxl21:CT_ExternalBookAlternateUrls/xxl21:alternateUrls",
+      "ClassName": "ExternalBookAlternateUrls",
+      "Summary": "Defines the ExternalBookAlternateUrls Class.",
+      "CompositeType": "OneSequence",
+      "BaseClass": "OpenXmlCompositeElement",
+      "Version": "Microsoft365",
+      "Attributes": [
+        {
+          "QName": ":driveId",
+          "Type": "StringValue",
+          "Version": "Microsoft365",
+          "PropertyComments": "driveId"
+        },
+        {
+          "QName": ":itemId",
+          "Type": "StringValue",
+          "Version": "Microsoft365",
+          "PropertyComments": "itemId"
+        }
+      ],
+      "Children": [
+        {
+          "Name": "xxl21:CT_AlternateUrl/xxl21:absoluteUrl",
+          "PropertyName": "AbsoluteUrlAlternateUrl"
+        },
+        {
+          "Name": "xxl21:CT_AlternateUrl/xxl21:relativeUrl",
+          "PropertyName": "RelativeUrlAlternateUrl"
+        }
+      ],
+      "Particle": {
+        "Kind": "Sequence",
+        "Items": [
+          {
+            "Name": "xxl21:CT_AlternateUrl/xxl21:absoluteUrl",
+            "Occurs": [
+              {
+                "Max": 1
+              }
+            ],
+            "InitialVersion": "Microsoft365"
+          },
+          {
+            "Name": "xxl21:CT_AlternateUrl/xxl21:relativeUrl",
+            "Occurs": [
+              {
+                "Max": 1
+              }
+            ],
+            "InitialVersion": "Microsoft365"
+          }
+        ]
+      }
+    },
+    {
+      "Name": "xxl21:CT_AlternateUrl/xxl21:absoluteUrl",
+      "ClassName": "AbsoluteUrlAlternateUrl",
+      "Summary": "Defines the AbsoluteUrlAlternateUrl Class.",
+      "BaseClass": "OpenXmlAlternateUrlElement",
+      "IsDerived": true,
+      "IsLeafElement": true,
+      "Version": "Microsoft365"
+    },
+    {
+      "Name": "xxl21:CT_AlternateUrl/xxl21:relativeUrl",
+      "ClassName": "RelativeUrlAlternateUrl",
+      "Summary": "Defines the RelativeUrlAlternateUrl Class.",
+      "BaseClass": "OpenXmlAlternateUrlElement",
+      "IsDerived": true,
+      "IsLeafElement": true,
+      "Version": "Microsoft365"
+    },
+    {
+      "Name": "xxl21:CT_AlternateUrl/",
+      "ClassName": "OpenXmlAlternateUrlElement",
+      "Summary": "Defines the OpenXmlAlternateUrlElement Class.",
+      "BaseClass": "OpenXmlLeafElement",
+      "IsAbstract": true,
+      "IsLeafElement": true,
+      "Version": "Microsoft365",
+      "Attributes": [
+        {
+          "QName": "r:id",
+          "Type": "StringValue",
+          "Version": "Microsoft365",
+          "PropertyComments": "id",
+          "Validators": [
+            {
+              "Name": "RequiredValidator"
+            }
+          ]
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/data/schemas/schemas_openxmlformats_org_spreadsheetml_2006_main.json b/data/schemas/schemas_openxmlformats_org_spreadsheetml_2006_main.json
index 7743dafa5..88de641e5 100644
--- a/data/schemas/schemas_openxmlformats_org_spreadsheetml_2006_main.json
+++ b/data/schemas/schemas_openxmlformats_org_spreadsheetml_2006_main.json
@@ -16478,77 +16478,6 @@
         }
       ]
     },
-    {
-      "Name": "x:CT_ExternalSheetNames/x:sheetNames",
-      "ClassName": "SheetNames",
-      "Summary": "Supporting Workbook Sheet Names.",
-      "BaseClass": "OpenXmlCompositeElement",
-      "Children": [
-        {
-          "Name": "x:CT_ExternalSheetName/x:sheetName"
-        }
-      ],
-      "Particle": {
-        "Kind": "Sequence",
-        "Items": [
-          {
-            "Name": "x:CT_ExternalSheetName/x:sheetName",
-            "Occurs": [
-              {
-                "Min": 1,
-                "Max": 65534
-              }
-            ]
-          }
-        ]
-      }
-    },
-    {
-      "Name": "x:CT_ExternalDefinedNames/x:definedNames",
-      "ClassName": "ExternalDefinedNames",
-      "Summary": "Named Links.",
-      "BaseClass": "OpenXmlCompositeElement",
-      "Children": [
-        {
-          "Name": "x:CT_ExternalDefinedName/x:definedName"
-        }
-      ],
-      "Particle": {
-        "Kind": "Sequence",
-        "Items": [
-          {
-            "Name": "x:CT_ExternalDefinedName/x:definedName",
-            "Occurs": [
-              {}
-            ]
-          }
-        ]
-      }
-    },
-    {
-      "Name": "x:CT_ExternalSheetDataSet/x:sheetDataSet",
-      "ClassName": "SheetDataSet",
-      "Summary": "Cached Worksheet Data.",
-      "BaseClass": "OpenXmlCompositeElement",
-      "Children": [
-        {
-          "Name": "x:CT_ExternalSheetData/x:sheetData"
-        }
-      ],
-      "Particle": {
-        "Kind": "Sequence",
-        "Items": [
-          {
-            "Name": "x:CT_ExternalSheetData/x:sheetData",
-            "Occurs": [
-              {
-                "Min": 1
-              }
-            ]
-          }
-        ]
-      }
-    },
     {
       "Name": "x:CT_ExternalDefinedName/x:definedName",
       "ClassName": "ExternalDefinedName",
@@ -16901,25 +16830,39 @@
         }
       ],
       "Children": [
+        {
+          "Name": "xxl21:CT_ExternalBookAlternateUrls/xxl21:alternateUrls",
+          "PropertyName": "ExternalBookAlternateUrls",
+          "PropertyComments": "Alternate URLs and identifiers of the external book"
+        },
         {
           "Name": "x:CT_ExternalSheetNames/x:sheetNames",
           "PropertyName": "SheetNames",
-          "PropertyComments": "Supporting Workbook Sheet Names"
+          "PropertyComments": "Sheet names of supporting book"
         },
         {
           "Name": "x:CT_ExternalDefinedNames/x:definedNames",
           "PropertyName": "ExternalDefinedNames",
-          "PropertyComments": "Named Links"
+          "PropertyComments": "Defined names associated with supporting book."
         },
         {
           "Name": "x:CT_ExternalSheetDataSet/x:sheetDataSet",
           "PropertyName": "SheetDataSet",
-          "PropertyComments": "Cached Worksheet Data"
+          "PropertyComments": "Cached worksheet data associated with supporting book"
         }
       ],
       "Particle": {
         "Kind": "Sequence",
         "Items": [
+          {
+            "Name": "xxl21:CT_ExternalBookAlternateUrls/xxl21:alternateUrls",
+            "Occurs": [
+              {
+                "Max": 1
+              }
+            ],
+            "InitialVersion": "Microsoft365"
+          },
           {
             "Name": "x:CT_ExternalSheetNames/x:sheetNames",
             "Occurs": [
@@ -25454,6 +25397,77 @@
           }
         ]
       }
+    },
+    {
+      "Name": "x:CT_ExternalSheetNames/x:sheetNames",
+      "ClassName": "SheetNames",
+      "Summary": "Sheet names of supporting book.",
+      "BaseClass": "OpenXmlCompositeElement",
+      "Children": [
+        {
+          "Name": "x:CT_ExternalSheetName/x:sheetName"
+        }
+      ],
+      "Particle": {
+        "Kind": "Sequence",
+        "Items": [
+          {
+            "Name": "x:CT_ExternalSheetName/x:sheetName",
+            "Occurs": [
+              {
+                "Min": 1,
+                "Max": 65534
+              }
+            ]
+          }
+        ]
+      }
+    },
+    {
+      "Name": "x:CT_ExternalDefinedNames/x:definedNames",
+      "ClassName": "ExternalDefinedNames",
+      "Summary": "Defined names associated with supporting book..",
+      "BaseClass": "OpenXmlCompositeElement",
+      "Children": [
+        {
+          "Name": "x:CT_ExternalDefinedName/x:definedName"
+        }
+      ],
+      "Particle": {
+        "Kind": "Sequence",
+        "Items": [
+          {
+            "Name": "x:CT_ExternalDefinedName/x:definedName",
+            "Occurs": [
+              {}
+            ]
+          }
+        ]
+      }
+    },
+    {
+      "Name": "x:CT_ExternalSheetDataSet/x:sheetDataSet",
+      "ClassName": "SheetDataSet",
+      "Summary": "Cached worksheet data associated with supporting book.",
+      "BaseClass": "OpenXmlCompositeElement",
+      "Children": [
+        {
+          "Name": "x:CT_ExternalSheetData/x:sheetData"
+        }
+      ],
+      "Particle": {
+        "Kind": "Sequence",
+        "Items": [
+          {
+            "Name": "x:CT_ExternalSheetData/x:sheetData",
+            "Occurs": [
+              {
+                "Min": 1
+              }
+            ]
+          }
+        ]
+      }
     }
   ],
   "Enums": [
diff --git a/data/schemas/schemas_openxmlformats_org_wordprocessingml_2006_main.json b/data/schemas/schemas_openxmlformats_org_wordprocessingml_2006_main.json
index dde62adb7..f80be4971 100644
--- a/data/schemas/schemas_openxmlformats_org_wordprocessingml_2006_main.json
+++ b/data/schemas/schemas_openxmlformats_org_wordprocessingml_2006_main.json
@@ -29293,7 +29293,7 @@
     {
       "Name": "w:CT_NonNegativeDecimalNumber/w:abstractNumId",
       "ClassName": "AbstractNumId",
-      "Summary": "Abstract Numbering Definition Reference.",
+      "Summary": "Defines the AbstractNumId Class.",
       "BaseClass": "NonNegativeDecimalNumberType",
       "IsDerived": true,
       "IsLeafElement": true
@@ -40284,59 +40284,6 @@
         ]
       }
     },
-    {
-      "Name": "w:CT_NumLvl/w:lvlOverride",
-      "ClassName": "LevelOverride",
-      "Summary": "Numbering Level Definition Override.",
-      "CompositeType": "OneSequence",
-      "BaseClass": "OpenXmlCompositeElement",
-      "Attributes": [
-        {
-          "QName": "w:ilvl",
-          "PropertyName": "LevelIndex",
-          "Type": "Int32Value",
-          "PropertyComments": "Numbering Level ID",
-          "Validators": [
-            {
-              "Name": "RequiredValidator"
-            }
-          ]
-        }
-      ],
-      "Children": [
-        {
-          "Name": "w:CT_DecimalNumber/w:startOverride",
-          "PropertyName": "StartOverrideNumberingValue",
-          "PropertyComments": "Numbering Level Starting Value Override"
-        },
-        {
-          "Name": "w:CT_Lvl/w:lvl",
-          "PropertyName": "Level",
-          "PropertyComments": "Numbering Level Override Definition"
-        }
-      ],
-      "Particle": {
-        "Kind": "Sequence",
-        "Items": [
-          {
-            "Name": "w:CT_DecimalNumber/w:startOverride",
-            "Occurs": [
-              {
-                "Max": 1
-              }
-            ]
-          },
-          {
-            "Name": "w:CT_Lvl/w:lvl",
-            "Occurs": [
-              {
-                "Max": 1
-              }
-            ]
-          }
-        ]
-      }
-    },
     {
       "Name": "w:CT_NumPicBullet/w:numPicBullet",
       "ClassName": "NumberingPictureBullet",
@@ -40521,19 +40468,23 @@
           "QName": "w:numId",
           "PropertyName": "NumberID",
           "Type": "Int32Value",
-          "PropertyComments": "Numbering Definition Instance ID",
+          "PropertyComments": "numId",
           "Validators": [
             {
               "Name": "RequiredValidator"
             }
           ]
+        },
+        {
+          "QName": "w:durableId",
+          "Type": "Int32Value",
+          "PropertyComments": "durableId"
         }
       ],
       "Children": [
         {
           "Name": "w:CT_NonNegativeDecimalNumber/w:abstractNumId",
-          "PropertyName": "AbstractNumId",
-          "PropertyComments": "Abstract Numbering Definition Reference"
+          "PropertyName": "AbstractNumId"
         },
         {
           "Name": "w:CT_NumLvl/w:lvlOverride"
@@ -51361,6 +51312,59 @@
           ]
         }
       ]
+    },
+    {
+      "Name": "w:CT_NumLvl/w:lvlOverride",
+      "ClassName": "LevelOverride",
+      "Summary": "Defines the LevelOverride Class.",
+      "CompositeType": "OneSequence",
+      "BaseClass": "OpenXmlCompositeElement",
+      "Attributes": [
+        {
+          "QName": "w:ilvl",
+          "PropertyName": "LevelIndex",
+          "Type": "Int32Value",
+          "PropertyComments": "Numbering Level ID",
+          "Validators": [
+            {
+              "Name": "RequiredValidator"
+            }
+          ]
+        }
+      ],
+      "Children": [
+        {
+          "Name": "w:CT_DecimalNumber/w:startOverride",
+          "PropertyName": "StartOverrideNumberingValue",
+          "PropertyComments": "Numbering Level Starting Value Override"
+        },
+        {
+          "Name": "w:CT_Lvl/w:lvl",
+          "PropertyName": "Level",
+          "PropertyComments": "Numbering Level Override Definition"
+        }
+      ],
+      "Particle": {
+        "Kind": "Sequence",
+        "Items": [
+          {
+            "Name": "w:CT_DecimalNumber/w:startOverride",
+            "Occurs": [
+              {
+                "Max": 1
+              }
+            ]
+          },
+          {
+            "Name": "w:CT_Lvl/w:lvl",
+            "Occurs": [
+              {
+                "Max": 1
+              }
+            ]
+          }
+        ]
+      }
     }
   ],
   "Enums": [
diff --git a/data/typed/namespaces.json b/data/typed/namespaces.json
index 7d5f82d39..aa011e2f5 100644
--- a/data/typed/namespaces.json
+++ b/data/typed/namespaces.json
@@ -127,6 +127,10 @@
     "Prefix": "p216",
     "Namespace": "DocumentFormat.OpenXml.Office.PowerPoint.Y2021.M06.Main"
   },
+  {
+    "Prefix": "xxl21",
+    "Namespace": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021"
+  },
   {
     "Prefix": "xxpvi",
     "Namespace": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2022.PivotVersionInfo"
diff --git a/data/typed/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json b/data/typed/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json
new file mode 100644
index 000000000..ef95adabf
--- /dev/null
+++ b/data/typed/schemas_microsoft_com_office_spreadsheetml_2021_extlinks2021.json
@@ -0,0 +1,18 @@
+[
+  {
+    "Name": "xxl21:CT_AlternateUrl/",
+    "ClassName": "OpenXmlAlternateUrlElement"
+  },
+  {
+    "Name": "xxl21:CT_AlternateUrl/xxl21:absoluteUrl",
+    "ClassName": "AbsoluteUrlAlternateUrl"
+  },
+  {
+    "Name": "xxl21:CT_ExternalBookAlternateUrls/xxl21:alternateUrls",
+    "ClassName": "ExternalBookAlternateUrls"
+  },
+  {
+    "Name": "xxl21:CT_AlternateUrl/xxl21:relativeUrl",
+    "ClassName": "RelativeUrlAlternateUrl"
+  }
+]
\ No newline at end of file
diff --git a/test/DocumentFormat.OpenXml.Framework.Tests/ElementChildren.json b/test/DocumentFormat.OpenXml.Framework.Tests/ElementChildren.json
index 9252b679d..35397b1cd 100644
--- a/test/DocumentFormat.OpenXml.Framework.Tests/ElementChildren.json
+++ b/test/DocumentFormat.OpenXml.Framework.Tests/ElementChildren.json
@@ -22331,6 +22331,27 @@
     "Element": "DocumentFormat.OpenXml.Office.PowerPoint.Y2021.M06.Main.UnasgnAllEmpty",
     "Children": []
   },
+  {
+    "Element": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.AbsoluteUrlAlternateUrl",
+    "Children": []
+  },
+  {
+    "Element": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.ExternalBookAlternateUrls",
+    "Children": [
+      {
+        "Name": "absoluteUrl",
+        "Namespace": "http://schemas.microsoft.com/office/spreadsheetml/2021/extlinks2021"
+      },
+      {
+        "Name": "relativeUrl",
+        "Namespace": "http://schemas.microsoft.com/office/spreadsheetml/2021/extlinks2021"
+      }
+    ]
+  },
+  {
+    "Element": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.RelativeUrlAlternateUrl",
+    "Children": []
+  },
   {
     "Element": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2022.PivotVersionInfo.CacheVersionInfo",
     "Children": [
@@ -43232,6 +43253,10 @@
   {
     "Element": "DocumentFormat.OpenXml.Spreadsheet.ExternalBook",
     "Children": [
+      {
+        "Name": "alternateUrls",
+        "Namespace": "http://schemas.microsoft.com/office/spreadsheetml/2021/extlinks2021"
+      },
       {
         "Name": "definedNames",
         "Namespace": "http://schemas.openxmlformats.org/spreadsheetml/2006/main"
diff --git a/test/DocumentFormat.OpenXml.Packaging.Tests/data/Particles.json b/test/DocumentFormat.OpenXml.Packaging.Tests/data/Particles.json
index a6df3f649..e052a3c62 100644
--- a/test/DocumentFormat.OpenXml.Packaging.Tests/data/Particles.json
+++ b/test/DocumentFormat.OpenXml.Packaging.Tests/data/Particles.json
@@ -33506,6 +33506,27 @@
    }
   ]
  },
+ {
+  "Key": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.ExternalBookAlternateUrls",
+  "Value": [
+   {
+    "Key": "Microsoft365",
+    "Value": {
+     "ChildrenParticles": [
+      {
+       "ElementType": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.AbsoluteUrlAlternateUrl",
+       "MinOccurs": 0
+      },
+      {
+       "ElementType": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.RelativeUrlAlternateUrl",
+       "MinOccurs": 0
+      }
+     ],
+     "ParticleType": "Sequence"
+    }
+   }
+  ]
+ },
  {
   "Key": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2022.PivotVersionInfo.CacheVersionInfo",
   "Value": [
@@ -62045,9 +62066,33 @@
   "Key": "DocumentFormat.OpenXml.Spreadsheet.ExternalBook",
   "Value": [
    {
-    "Key": "Office2007, Office2010, Office2013, Office2016, Office2019, Office2021, Microsoft365",
+    "Key": "Office2007, Office2010, Office2013, Office2016, Office2019, Office2021",
+    "Value": {
+     "ChildrenParticles": [
+      {
+       "ElementType": "DocumentFormat.OpenXml.Spreadsheet.SheetNames",
+       "MinOccurs": 0
+      },
+      {
+       "ElementType": "DocumentFormat.OpenXml.Spreadsheet.ExternalDefinedNames",
+       "MinOccurs": 0
+      },
+      {
+       "ElementType": "DocumentFormat.OpenXml.Spreadsheet.SheetDataSet",
+       "MinOccurs": 0
+      }
+     ],
+     "ParticleType": "Sequence"
+    }
+   },
+   {
+    "Key": "Microsoft365",
     "Value": {
      "ChildrenParticles": [
+      {
+       "ElementType": "DocumentFormat.OpenXml.Office.SpreadSheetML.Y2021.ExtLinks2021.ExternalBookAlternateUrls",
+       "MinOccurs": 0
+      },
       {
        "ElementType": "DocumentFormat.OpenXml.Spreadsheet.SheetNames",
        "MinOccurs": 0