diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageBuilder{TPackage}.cs b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageBuilder{TPackage}.cs
index 34a4cbc23..2ef5f64fa 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageBuilder{TPackage}.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageBuilder{TPackage}.cs
@@ -11,7 +11,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// <summary>
 /// A delegate for initializing a package.
 /// </summary>
-public delegate void PackageInitializerDelegate<TPackage>(TPackage package);
+internal delegate void PackageInitializerDelegate<TPackage>(TPackage package);
 
 /// <summary>
 /// Defines a builder to create an initialization pipeline for a <typeparamref name="TPackage"/>.
@@ -19,7 +19,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// <typeparam name="TPackage">Type of the <see cref="OpenXmlPackage"/>.</typeparam>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public interface IPackageBuilder<TPackage>
+internal interface IPackageBuilder<TPackage>
     where TPackage : OpenXmlPackage
 {
     /// <summary>
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageDocumentBuilder.cs b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageDocumentBuilder.cs
index 3d0bae1bc..5ce25dd1e 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageDocumentBuilder.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageDocumentBuilder.cs
@@ -13,7 +13,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// <typeparam name="TPackage">Type of <see cref="OpenXmlPackage"/>.</typeparam>
 [System.Diagnostics.CodeAnalysis.SuppressMessage("Design", "CA1000:Do not declare static members on generic types", Justification = "Static abstract interface types")]
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public interface IPackageDocumentBuilder<TPackage> where TPackage : OpenXmlPackage, IPackageDocumentBuilder<TPackage>
+internal interface IPackageDocumentBuilder<TPackage> where TPackage : OpenXmlPackage, IPackageDocumentBuilder<TPackage>
 {
     /// <summary>
     /// Creates a default builder for <typeparamref name="TPackage"/>.
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageFactory.cs b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageFactory.cs
index d7c18acc6..7410a212c 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/IPackageFactory.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/IPackageFactory.cs
@@ -14,7 +14,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// <typeparam name="TPackage">Type of the <see cref="OpenXmlPackage"/>.</typeparam>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public interface IPackageFactory<TPackage>
+internal interface IPackageFactory<TPackage>
 {
     /// <summary>
     /// Create an instance of <typeparamref name="TPackage"/>.
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/OpenXmlPackageBuilderExtensions.cs b/src/DocumentFormat.OpenXml.Framework/Builder/OpenXmlPackageBuilderExtensions.cs
index 4f81475e8..ab22d1de2 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/OpenXmlPackageBuilderExtensions.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/OpenXmlPackageBuilderExtensions.cs
@@ -15,7 +15,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// </summary>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public static class OpenXmlPackageBuilderExtensions
+internal static class OpenXmlPackageBuilderExtensions
 {
     /// <summary>
     /// Opens the <paramref name="stream"/> with the given <paramref name="mode"/>.
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/PackageOpenMode.cs b/src/DocumentFormat.OpenXml.Framework/Builder/PackageOpenMode.cs
index 61cc37807..45c556d3d 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/PackageOpenMode.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/PackageOpenMode.cs
@@ -11,7 +11,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// </summary>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public enum PackageOpenMode
+internal enum PackageOpenMode
 {
     /// <summary>
     /// Indicates that a new package will be created.
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/SchemaTrackingExtensions.cs b/src/DocumentFormat.OpenXml.Framework/Builder/SchemaTrackingExtensions.cs
index a45df4ced..3cdc45724 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/SchemaTrackingExtensions.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/SchemaTrackingExtensions.cs
@@ -22,7 +22,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// </summary>
 [Experimental(ExperimentalApis.AOT, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.AOT, UrlFormat = ExperimentalApis.UrlFormat)]
-public static class SchemaTrackingExtensions
+internal static class SchemaTrackingExtensions
 {
     private const string Key = "__SchemaTracker";
 
diff --git a/src/DocumentFormat.OpenXml.Framework/Builder/TemplateBuilderExtensions.cs b/src/DocumentFormat.OpenXml.Framework/Builder/TemplateBuilderExtensions.cs
index c0a469c4f..9c240d87f 100644
--- a/src/DocumentFormat.OpenXml.Framework/Builder/TemplateBuilderExtensions.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Builder/TemplateBuilderExtensions.cs
@@ -14,7 +14,7 @@ namespace DocumentFormat.OpenXml.Builder;
 /// </summary>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public static class TemplateBuilderExtensions
+internal static class TemplateBuilderExtensions
 {
     /// <summary>
     /// Adds a template to the current <paramref name="builder"/>.
diff --git a/src/DocumentFormat.OpenXml.Framework/Features/IPackageInitializer.cs b/src/DocumentFormat.OpenXml.Framework/Features/IPackageInitializer.cs
index 775ef5bdb..697fa5973 100644
--- a/src/DocumentFormat.OpenXml.Framework/Features/IPackageInitializer.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Features/IPackageInitializer.cs
@@ -12,7 +12,7 @@ namespace DocumentFormat.OpenXml.Features;
 /// </summary>
 [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-public interface IPackageInitializer
+internal interface IPackageInitializer
 {
     /// <summary>
     /// Initializes a package.
diff --git a/src/DocumentFormat.OpenXml.Framework/Features/ISchemaTrackingFeature.cs b/src/DocumentFormat.OpenXml.Framework/Features/ISchemaTrackingFeature.cs
index e9e286ee8..75d618a84 100644
--- a/src/DocumentFormat.OpenXml.Framework/Features/ISchemaTrackingFeature.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Features/ISchemaTrackingFeature.cs
@@ -13,7 +13,7 @@ namespace DocumentFormat.OpenXml.Features;
 /// </summary>
 [Experimental(ExperimentalApis.AOT, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.AOT, UrlFormat = ExperimentalApis.UrlFormat)]
-public interface ISchemaTrackingFeature
+internal interface ISchemaTrackingFeature
 {
     /// <summary>
     /// Gets a collection of root elements that have been requested.
diff --git a/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlNamespace.cs b/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlNamespace.cs
index 76307d57b..ad4675aac 100644
--- a/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlNamespace.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlNamespace.cs
@@ -11,7 +11,7 @@ namespace DocumentFormat.OpenXml.Framework;
 /// </summary>
 [Experimental(ExperimentalApis.Framework, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.Framework, UrlFormat = ExperimentalApis.UrlFormat)]
-public readonly partial struct OpenXmlNamespace : IComparable<OpenXmlNamespace>, IEquatable<OpenXmlNamespace>
+internal readonly partial struct OpenXmlNamespace : IComparable<OpenXmlNamespace>, IEquatable<OpenXmlNamespace>
 {
     private readonly string? _uri;
 
diff --git a/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlQualifiedName.cs b/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlQualifiedName.cs
index f5d7228f7..8d2102b78 100644
--- a/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlQualifiedName.cs
+++ b/src/DocumentFormat.OpenXml.Framework/Framework/OpenXmlQualifiedName.cs
@@ -11,7 +11,7 @@ namespace DocumentFormat.OpenXml.Framework;
 /// </summary>
 [Experimental(ExperimentalApis.Framework, UrlFormat = ExperimentalApis.UrlFormat)]
 [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.Framework, UrlFormat = ExperimentalApis.UrlFormat)]
-public readonly struct OpenXmlQualifiedName : IComparable<OpenXmlQualifiedName>, IEquatable<OpenXmlQualifiedName>
+internal readonly struct OpenXmlQualifiedName : IComparable<OpenXmlQualifiedName>, IEquatable<OpenXmlQualifiedName>
 {
     internal OpenXmlQualifiedName(in OpenXmlNamespace ns, string name)
     {
diff --git a/src/DocumentFormat.OpenXml.Framework/PublicAPI/PublicAPI.Unshipped.txt b/src/DocumentFormat.OpenXml.Framework/PublicAPI/PublicAPI.Unshipped.txt
index c67cfd56c..ab058de62 100644
--- a/src/DocumentFormat.OpenXml.Framework/PublicAPI/PublicAPI.Unshipped.txt
+++ b/src/DocumentFormat.OpenXml.Framework/PublicAPI/PublicAPI.Unshipped.txt
@@ -1,61 +1 @@
 #nullable enable
-DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage>
-DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage>.Build() -> DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage!>!
-DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage>.Clone() -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage>.Properties.get -> System.Collections.Generic.IDictionary<string!, object?>!
-DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage>.Use(System.Func<DocumentFormat.OpenXml.Builder.PackageInitializerDelegate<TPackage!>!, DocumentFormat.OpenXml.Builder.PackageInitializerDelegate<TPackage!>!>! configure) -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage>
-DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage>.Create(DocumentFormat.OpenXml.Features.IPackageInitializer! initializer) -> TPackage
-DocumentFormat.OpenXml.Builder.OpenXmlPackageBuilderExtensions
-DocumentFormat.OpenXml.Builder.PackageInitializerDelegate<TPackage>
-DocumentFormat.OpenXml.Builder.PackageOpenMode
-DocumentFormat.OpenXml.Builder.PackageOpenMode.Create = 0 -> DocumentFormat.OpenXml.Builder.PackageOpenMode
-DocumentFormat.OpenXml.Builder.PackageOpenMode.Read = 1 -> DocumentFormat.OpenXml.Builder.PackageOpenMode
-DocumentFormat.OpenXml.Builder.PackageOpenMode.ReadWrite = 2 -> DocumentFormat.OpenXml.Builder.PackageOpenMode
-DocumentFormat.OpenXml.Builder.SchemaTrackingExtensions
-DocumentFormat.OpenXml.Builder.TemplateBuilderExtensions
-DocumentFormat.OpenXml.Features.IPackageInitializer
-DocumentFormat.OpenXml.Features.IPackageInitializer.Initialize(DocumentFormat.OpenXml.Packaging.OpenXmlPackage! package) -> void
-DocumentFormat.OpenXml.Features.ISchemaTrackingFeature
-DocumentFormat.OpenXml.Features.ISchemaTrackingFeature.Relationships.get -> System.Collections.Generic.ICollection<string!>!
-DocumentFormat.OpenXml.Features.ISchemaTrackingFeature.RootElements.get -> System.Collections.Generic.ICollection<DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName>!
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.CompareTo(DocumentFormat.OpenXml.Framework.OpenXmlNamespace other) -> int
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.Equals(DocumentFormat.OpenXml.Framework.OpenXmlNamespace other) -> bool
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.IsEmpty.get -> bool
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.OpenXmlNamespace() -> void
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.OpenXmlNamespace(string! nsUri) -> void
-DocumentFormat.OpenXml.Framework.OpenXmlNamespace.Uri.get -> string!
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.CompareTo(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName other) -> int
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.Equals(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName other) -> bool
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.Name.get -> string!
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.Namespace.get -> DocumentFormat.OpenXml.Framework.OpenXmlNamespace
-DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.OpenXmlQualifiedName() -> void
-override DocumentFormat.OpenXml.Framework.OpenXmlNamespace.Equals(object? obj) -> bool
-override DocumentFormat.OpenXml.Framework.OpenXmlNamespace.GetHashCode() -> int
-override DocumentFormat.OpenXml.Framework.OpenXmlNamespace.ToString() -> string!
-override DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.Equals(object? obj) -> bool
-override DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.GetHashCode() -> int
-override DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.ToString() -> string!
-static DocumentFormat.OpenXml.Builder.OpenXmlPackageBuilderExtensions.Open<TPackage>(this DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage!>! builder, string! file, DocumentFormat.OpenXml.Builder.PackageOpenMode mode) -> TPackage!
-static DocumentFormat.OpenXml.Builder.OpenXmlPackageBuilderExtensions.Open<TPackage>(this DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage!>! builder, System.IO.Packaging.Package! package) -> TPackage!
-static DocumentFormat.OpenXml.Builder.OpenXmlPackageBuilderExtensions.Open<TPackage>(this DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage!>! builder, System.IO.Stream! stream, DocumentFormat.OpenXml.Builder.PackageOpenMode mode) -> TPackage!
-static DocumentFormat.OpenXml.Builder.OpenXmlPackageBuilderExtensions.Use<TPackage>(this DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>! builder, System.Action<TPackage!, DocumentFormat.OpenXml.Builder.PackageInitializerDelegate<TPackage!>!>! middleware) -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-static DocumentFormat.OpenXml.Builder.SchemaTrackingExtensions.GetSchemaTracker<T>(this DocumentFormat.OpenXml.Builder.IPackageBuilder<T!>! builder) -> DocumentFormat.OpenXml.Features.ISchemaTrackingFeature!
-static DocumentFormat.OpenXml.Builder.SchemaTrackingExtensions.UseSchemaTracker<T>(this DocumentFormat.OpenXml.Builder.IPackageBuilder<T!>! builder) -> DocumentFormat.OpenXml.Builder.IPackageBuilder<T!>!
-static DocumentFormat.OpenXml.Builder.TemplateBuilderExtensions.UseTemplate<TPackage, TType>(this DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>! builder, string! path, TType type) -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.implicit operator DocumentFormat.OpenXml.Framework.OpenXmlNamespace(string! nsUri) -> DocumentFormat.OpenXml.Framework.OpenXmlNamespace
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator !=(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator <(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator <=(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator ==(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator >(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlNamespace.operator >=(DocumentFormat.OpenXml.Framework.OpenXmlNamespace left, DocumentFormat.OpenXml.Framework.OpenXmlNamespace right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator !=(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator <(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator <=(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator ==(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator >(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-static DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName.operator >=(DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName left, DocumentFormat.OpenXml.Framework.OpenXmlQualifiedName right) -> bool
-virtual DocumentFormat.OpenXml.Builder.PackageInitializerDelegate<TPackage>.Invoke(TPackage package) -> void
diff --git a/src/DocumentFormat.OpenXml.Framework/PublicAPI/net8.0/PublicAPI.Unshipped.txt b/src/DocumentFormat.OpenXml.Framework/PublicAPI/net8.0/PublicAPI.Unshipped.txt
index 79169975c..e2eebeccc 100644
--- a/src/DocumentFormat.OpenXml.Framework/PublicAPI/net8.0/PublicAPI.Unshipped.txt
+++ b/src/DocumentFormat.OpenXml.Framework/PublicAPI/net8.0/PublicAPI.Unshipped.txt
@@ -1,5 +1,2 @@
 #nullable enable
-DocumentFormat.OpenXml.Builder.IPackageDocumentBuilder<TPackage>
-DocumentFormat.OpenXml.Builder.IPackageDocumentBuilder<TPackage>.CreateBuilder() -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-DocumentFormat.OpenXml.Builder.IPackageDocumentBuilder<TPackage>.CreateDefaultBuilder() -> DocumentFormat.OpenXml.Builder.IPackageBuilder<TPackage!>!
-DocumentFormat.OpenXml.Builder.IPackageDocumentBuilder<TPackage>.DefaultFactory.get -> DocumentFormat.OpenXml.Builder.IPackageFactory<TPackage!>!
+
diff --git a/src/DocumentFormat.OpenXml/Packaging/PresentationDocument.cs b/src/DocumentFormat.OpenXml/Packaging/PresentationDocument.cs
index ceb571a19..fd628abf5 100644
--- a/src/DocumentFormat.OpenXml/Packaging/PresentationDocument.cs
+++ b/src/DocumentFormat.OpenXml/Packaging/PresentationDocument.cs
@@ -15,12 +15,7 @@ namespace DocumentFormat.OpenXml.Packaging
     /// Defines PresentationDocument - an OpenXmlPackage represents a Presentation document
     /// </summary>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Reliability", "CA2000:Dispose objects before losing scope", Justification = "Disposable is returned")]
-    public partial class PresentationDocument :
-#if NET7_0_OR_GREATER
-        OpenXmlPackage, IPackageDocumentBuilder<PresentationDocument>
-#else
-        OpenXmlPackage
-#endif
+    public partial class PresentationDocument : OpenXmlPackage
     {
         internal PresentationDocument()
             : base()
@@ -35,7 +30,7 @@ internal PresentationDocument()
         /// <returns>The default builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<PresentationDocument> CreateBuilder() => new Builder();
+        internal static IPackageBuilder<PresentationDocument> CreateBuilder() => new Builder();
 
         /// <summary>
         /// Creates a builder that has minimal initialization for <see cref="PresentationDocument"/>.
@@ -43,14 +38,14 @@ internal PresentationDocument()
         /// <returns>A minimal builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<PresentationDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
+        internal static IPackageBuilder<PresentationDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
 
         /// <summary>
         /// Gets the default factory for <see cref="PresentationDocument"/>.
         /// </summary>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageFactory<PresentationDocument> DefaultFactory { get; } = DefaultBuilder.Build();
+        internal static IPackageFactory<PresentationDocument> DefaultFactory { get; } = DefaultBuilder.Build();
 
         private sealed class Builder : OpenXmlPackageBuilder<PresentationDocument>
         {
diff --git a/src/DocumentFormat.OpenXml/Packaging/SpreadsheetDocument.cs b/src/DocumentFormat.OpenXml/Packaging/SpreadsheetDocument.cs
index 874dae9c5..7c2a77904 100644
--- a/src/DocumentFormat.OpenXml/Packaging/SpreadsheetDocument.cs
+++ b/src/DocumentFormat.OpenXml/Packaging/SpreadsheetDocument.cs
@@ -15,12 +15,7 @@ namespace DocumentFormat.OpenXml.Packaging
     /// Defines SpreadsheetDocument - an OpenXmlPackage represents a Spreadsheet document.
     /// </summary>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Reliability", "CA2000:Dispose objects before losing scope", Justification = "Disposable is returned")]
-    public partial class SpreadsheetDocument :
-#if NET7_0_OR_GREATER
-        OpenXmlPackage, IPackageDocumentBuilder<SpreadsheetDocument>
-#else
-        OpenXmlPackage
-#endif
+    public partial class SpreadsheetDocument : OpenXmlPackage
     {
         internal SpreadsheetDocument()
             : base()
@@ -35,7 +30,7 @@ internal SpreadsheetDocument()
         /// <returns>The default builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<SpreadsheetDocument> CreateBuilder() => new Builder();
+        internal static IPackageBuilder<SpreadsheetDocument> CreateBuilder() => new Builder();
 
         /// <summary>
         /// Creates a builder that has minimal initialization for <see cref="SpreadsheetDocument"/>.
@@ -43,14 +38,14 @@ internal SpreadsheetDocument()
         /// <returns>A minimal builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<SpreadsheetDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
+        internal static IPackageBuilder<SpreadsheetDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
 
         /// <summary>
         /// Gets the default factory for <see cref="SpreadsheetDocument"/>.
         /// </summary>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageFactory<SpreadsheetDocument> DefaultFactory { get; } = DefaultBuilder.Build();
+        internal static IPackageFactory<SpreadsheetDocument> DefaultFactory { get; } = DefaultBuilder.Build();
 
         private sealed class Builder : OpenXmlPackageBuilder<SpreadsheetDocument>
         {
diff --git a/src/DocumentFormat.OpenXml/Packaging/WordprocessingDocument.cs b/src/DocumentFormat.OpenXml/Packaging/WordprocessingDocument.cs
index eff630fef..7dd2e4d44 100644
--- a/src/DocumentFormat.OpenXml/Packaging/WordprocessingDocument.cs
+++ b/src/DocumentFormat.OpenXml/Packaging/WordprocessingDocument.cs
@@ -16,12 +16,7 @@ namespace DocumentFormat.OpenXml.Packaging
     /// Defines WordprocessingDocument - an OpenXmlPackage represents a Word document.
     /// </summary>
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Reliability", "CA2000:Dispose objects before losing scope", Justification = "Disposable is returned")]
-    public partial class WordprocessingDocument :
-#if NET7_0_OR_GREATER
-        OpenXmlPackage, IPackageDocumentBuilder<WordprocessingDocument>
-#else
-        OpenXmlPackage
-#endif
+    public partial class WordprocessingDocument : OpenXmlPackage
     {
         internal WordprocessingDocument()
             : base()
@@ -36,7 +31,7 @@ internal WordprocessingDocument()
         /// <returns>The default builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<WordprocessingDocument> CreateBuilder() => new Builder();
+        internal static IPackageBuilder<WordprocessingDocument> CreateBuilder() => new Builder();
 
         /// <summary>
         /// Creates a builder that has minimal initialization for <see cref="WordprocessingDocument"/>.
@@ -44,14 +39,14 @@ internal WordprocessingDocument()
         /// <returns>A minimal builder.</returns>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageBuilder<WordprocessingDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
+        internal static IPackageBuilder<WordprocessingDocument> CreateDefaultBuilder() => DefaultBuilder.Clone();
 
         /// <summary>
         /// Gets the default factory for <see cref="WordprocessingDocument"/>.
         /// </summary>
         [Experimental(ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
         [Obsolete(ExperimentalApis.Message, DiagnosticId = ExperimentalApis.PackageBuilder, UrlFormat = ExperimentalApis.UrlFormat)]
-        public static IPackageFactory<WordprocessingDocument> DefaultFactory { get; } = DefaultBuilder.Build();
+        internal static IPackageFactory<WordprocessingDocument> DefaultFactory { get; } = DefaultBuilder.Build();
 
         private sealed class Builder : OpenXmlPackageBuilder<WordprocessingDocument>
         {