diff --git a/src/libraries/System.IO.FileSystem.AccessControl/README.md b/src/libraries/System.IO.FileSystem.AccessControl/README.md
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+# System.IO.FileSystem.AccessControl
+This assembly provides support for controling access to and auditing security-related actions on securable objects.
+This assembly is only supported on Windows.
+
+Documentation can be found at https://learn.microsoft.com/dotnet/api/system.security.accesscontrol and https://learn.microsoft.com/dotnet/api/system.io.filesystemaclextensions.
+
+## Contribution Bar
+- [x] [We only consider fixes to maintain or improve quality](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.FileSystem.AccessControl assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.FileSystem.DriveInfo/README.md b/src/libraries/System.IO.FileSystem.DriveInfo/README.md
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+# System.IO.FileSystem.DriveInfo
+This assembly provides support for querying local drive information. The primary type in this assembly is [`DriveInfo`](https://learn.microsoft.com/dotnet/api/system.io.driveinfo).
+
+## Contribution Bar
+- [x] [We consider new features, new APIs and performance changes](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.FileSystem.DriveInfo assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.FileSystem.Primitives/README.md b/src/libraries/System.IO.FileSystem.Primitives/README.md
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+# System.IO.FileSystem.Primitives
+This assembly no longer contains any code. It is provided only to permit type unification for libraries built against previous versions of .NET.
+
+## Source
+* All types previously part of this assembly (`FileAccess`, `FileAttributes`, `FileMode`, `FileShare`) are now part of [System.Private.CoreLib](../System.Private.CoreLib/), exposed via [System.Runtime](../System.Runtime/).
+
+* Some tests for types previously in this library are still in the [tests](tests/) subdirectory.
+
+## Contribution Bar
+- [x] We consider changes that move tests from the [tests](tests/) subdirectory into [System.IO.Tests](../System.IO/tests/) project.
+
+## Deployment
+The System.IO.FileSystem.Primitives assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.FileSystem.Watcher/README.md b/src/libraries/System.IO.FileSystem.Watcher/README.md
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+# System.IO.FileSystem.Watcher
+This assembly provides support for watching directory changes through the class `FileSystemWatcher`.
+
+Documentation can be found at https://learn.microsoft.com/dotnet/api/system.io.filesystemwatcher.
+
+## Contribution Bar
+- [x] [We consider new features, new APIs and performance changes](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.FileSystem.Watcher assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.FileSystem/README.md b/src/libraries/System.IO.FileSystem/README.md
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+# System.IO.FileSystem
+This assembly no longer contains any code. It is provided only to permit type unification for libraries built against previous versions of .NET.
+
+## Source
+* All types previously part of this assembly (`FileStream`, `FileSystemInfo`, `FileSystemEnumerable`, etc.) are now part of [System.Private.CoreLib](../System.Private.CoreLib/), exposed via [System.Runtime](../System.Runtime/).
+
+* All of the tests for types previously in this library are still in the [tests](tests/) subdirectory.
+
+## Contribution Bar
+- [x] We consider changes that add value to the tests.
+
+## Deployment
+The System.IO.FileSystem assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.IsolatedStorage/README.md b/src/libraries/System.IO.IsolatedStorage/README.md
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+# System.IO.IsolatedStorage
+This assembly provides support for **standarized** isolated storages for applications at multiple scopes. The primary types in this assembly are [`IsolatedStorageFile`](https://learn.microsoft.com/dotnet/api/system.io.isolatedstorage.isolatedstoragefile) and [`IsolatedStorageFileStream`](https://learn.microsoft.com/dotnet/api/system.io.isolatedstorage.isolatedstoragefile).
+
+Documentation can be found at https://learn.microsoft.com/dotnet/api/system.io.isolatedstorage.
+
+## Contribution Bar
+- [x] [We only consider fixes to maintain or improve quality](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.IsolatedStorage assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.MemoryMappedFiles/README.md b/src/libraries/System.IO.MemoryMappedFiles/README.md
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+# System.IO.MemoryMappedFiles
+This assembly provides support for creating files into the Random-Access Memory of the application's machine. The primary types in this assembly are [`MemoryMappedFile`](https://learn.microsoft.com/dotnet/api/system.io.memorymappedfiles.memorymappedfile) used to create the in-memory file, and [`MemoryMappedViewAccessor`](https://learn.microsoft.com/dotnet/api/system.io.memorymappedfiles.memorymappedviewaccessor) and [`MemoryMappedViewStream`](https://learn.microsoft.com/dotnet/api/system.io.memorymappedfiles.memorymappedviewstream) to access the contents of the file.
+
+Documentation can be found at https://learn.microsoft.com/dotnet/api/system.io.memorymappedfiles.
+
+## Contribution Bar
+- [x] [We consider new features, new APIs and performance changes](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.MemoryMappedFiles assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.Pipes.AccessControl/README.md b/src/libraries/System.IO.Pipes.AccessControl/README.md
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+++ b/src/libraries/System.IO.Pipes.AccessControl/README.md
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+# System.IO.Pipes.AccessControl
+This assembly no longer contains executable code, it contains the code for the reference assembly and the tests for the types formerly implemented.
+
+## Source
+* All types previously implemented on this library are now part of [System.IO.Pipes](../System.IO.Pipes/) library.
+
+* Some of the tests for types previously in this library are still in the [tests](tests/) subdirectory.
+
+## Contribution Bar
+- [x] We consider changes that move tests from the [tests](tests/) subdirectory into [System.IO.Pipes.Tests](../System.IO.Pipes/tests/) project.
+
+## Deployment
+The System.IO.Pipes.AccessControl assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.Pipes/README.md b/src/libraries/System.IO.Pipes/README.md
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+++ b/src/libraries/System.IO.Pipes/README.md
@@ -0,0 +1,9 @@
+# System.IO.Pipes
+This assembly provides support for interprocess communication through anonymous and/or named pipes. The primary types in this assembly are [AnonymousPipeClientStream](https://learn.microsoft.com/dotnet/api/system.io.pipes.anonymouspipeclientstream), [AnonymousPipeServerStream](https://learn.microsoft.com/dotnet/api/system.io.pipes.anonymouspipeserverstream), [NamedPipeClientStream](https://learn.microsoft.com/dotnet/api/system.io.pipes.namedpipeclientstream), and [NamedPipeServerStream](https://learn.microsoft.com/dotnet/api/system.io.pipes.namedpipeserverstream).
+
+## Contribution Bar
+- [x] [We consider new features, new APIs and performance changes](../../libraries/README.md#primary-bar)
+- [x] [We consider PRs that target this library for new source code analyzers](../../libraries/README.md#secondary-bars)
+
+## Deployment
+The System.IO.Pipes assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO.UnmanagedMemoryStream/README.md b/src/libraries/System.IO.UnmanagedMemoryStream/README.md
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+++ b/src/libraries/System.IO.UnmanagedMemoryStream/README.md
@@ -0,0 +1,13 @@
+# System.IO.UnmanagedMemoryStream
+This assembly no longer contains any code.  It is provided only to permit type unification for libraries built against previous versions of .NET.
+
+## Source
+* All types previously part of this library are now part of [System.Private.CoreLib](../System.Private.CoreLib/), `UnmanagedMemoryAccessor` is exposed via [System.Runtime.InteropServices](../System.Runtime.InteropServices/) and `UnmanagedMemoryStream` is exposed via [System.Runtime](../System.Runtime/).
+
+* Some of the tests for types previously in this library are still in the [tests](tests/) subdirectory.
+
+## Contribution Bar
+- [x] We consider changes that move tests from the [tests](tests/) subdirectory into [System.IO.Tests](../System.IO/tests/) project.
+
+## Deployment
+The System.IO.UnmanagedMemoryStream assembly is part of the shared framework, and ships with every new release of .NET.
diff --git a/src/libraries/System.IO/README.md b/src/libraries/System.IO/README.md
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+++ b/src/libraries/System.IO/README.md
@@ -0,0 +1,13 @@
+# System.IO
+This assembly no longer contains any code. It is provided only to permit type unification for libraries built against previous versions of .NET.
+
+## Source
+* All types previously part of this assembly (`Stream`, `BinaryReader`, `MemoryStream`, `StreamReader`, `TextWriter`, etc.) are now part of [System.Private.CoreLib](../System.Private.CoreLib/), exposed via [System.Runtime](../System.Runtime/).
+
+* Most of the tests for types previously in this library are still in the [tests](tests/) subdirectory.
+
+## Contribution Bar
+- [x] We consider changes that add value to the tests.
+
+## Deployment
+The System.IO assembly is part of the shared framework, and ships with every new release of .NET.