diff --git a/docs/RegisteredFilterPlugins.md b/docs/RegisteredFilterPlugins.md
index ad5091f3..8bedfb5f 100644
--- a/docs/RegisteredFilterPlugins.md
+++ b/docs/RegisteredFilterPlugins.md
@@ -11,6 +11,7 @@ Any member of the HDF5 community can register a plugin for their or a third-part
* Maintainer's contact information. Minimum an email address, preferably additional information like personal website, GitHub or social network handles. More ways to contact the responsible maintainer is better.
* Filter plugin's respository.
* Description of the new plugin including the specifics of the filter parameters (`cd_nelmts` and `cd_values[]`) supported by the plugin.
+* A proposed **canonical name** for the filter. This is the short, stable string identifier that an `H5Z_class3_t` plugin will advertise in its `name` field and that the library will write into the on-disk filter-pipeline message. The canonical name must be non-empty, no more than 255 bytes, drawn from the character class `[A-Za-z0-9_.-]`, and is matched case-sensitively. See [Canonical Names](#canonical-names-h5z_class3_t-plugin-class) below for details. (Existing `H5Z_class1_t`/`H5Z_class2_t` plugins without a canonical name continue to work unchanged; this only becomes load-bearing when a plugin opts into the v3 plugin class.)
* Links to any relevant documentation, including the licensing information.
Upon receiving a request with the above information, HDF Group will register the new plugin by assigning it a filter plugin _identifier_. The current policy for assigning an identifier is explained below:
@@ -24,48 +25,88 @@ Upon receiving a request with the above information, HDF Group will register the
## List of Filter Plugins Registered with The HDF Group
-| Plugin Identifier | For Filter | Short Description|
-|--------|----------------|---------------------|
-|`257` |hzip |hzip compression used in Silo|
-|`258` |fpzip |Duplicate of plugin `32014`|
-|`305` |LZO |LZO lossless compression used by PyTables|
-|`307` |BZIP2 |BZIP2 lossless compression used by PyTables|
-|`32000` |LZF |LZF lossless compression used by the h5py package|
-|`32001` |BLOSC |Blosc lossless compression used by PyTables|
-|`32002` |MAFISC |Modified LZMA compression filter, MAFISC (Multidimensional Adaptive Filtering Improved Scientific data Compression)|
-|`32003` |Snappy |Snappy lossless compression|
-|`32004` |LZ4 |LZ4 fast lossless compression algorithm|
-|`32005` |APAX |Samplify’s APAX Numerical Encoding Technology|
-|`32006` |CBF |All imgCIF/CBF compressions and decompressions, including Canonical, Packed, Packed Version 2, Byte Offset and Nibble Offset|
-|`32007` |JPEG-XR |Enables images to be compressed/decompressed with JPEG-XR compression|
-|`32008` |bitshuffle |Extreme version of shuffle filter that shuffles data at bit level instead of byte level|
-|`32009` |SPDP |SPDP fast lossless compression algorithm for single- and double-precision floating-point data|
-|`32010` |LPC-Rice |LPC-Rice multi-threaded lossless compression|
-|`32011` |CCSDS-123 |ESA CCSDS-123 multi-threaded compression filter|
-|`32012` |JPEG-LS |CharLS JPEG-LS multi-threaded compression filter|
-|`32013` |zfp |Lossy & lossless compression of floating point and integer datasets to meet rate, accuracy, and/or precision targets.|
-|`32014` |fpzip |Fast and Efficient Lossy or Lossless Compressor for Floating-Point Data|
-|`32015` |Zstandard |Real-time compression algorithm with wide range of compression / speed trade-off and fast decoder|
-|`32016` |B³D |GPU based image compression method developed for light-microscopy applications|
-|`32017` |SZ |An error-bounded lossy compressor for scientific floating-point data|
-|`32018` |FCIDECOMP |EUMETSAT CharLS compression filter for use with netCDF|
-|`32019` |JPEG |Jpeg compression filter|
-|`32020` |VBZ |Compression filter for raw dna signal data used by Oxford Nanopore|
-|`32021` |FAPEC | Versatile and efficient data compressor supporting many kinds of data and using an outlier-resilient entropy coder|
-|`32022` |BitGroom |The BitGroom quantization algorithm|
-|`32023` |Granular BitRound (GBR) |The GBR quantization algorithm is a significant improvement to the BitGroom filter|
-|`32024` |SZ3 |A modular error-bounded lossy compression framework for scientific datasets|
-|`32025` |Delta-Rice |Lossless compression algorithm optimized for digitized analog signals based on delta encoding and rice coding|
-|`32026` |BLOSC2 |The recent new-generation version of the Blosc compression library|
-|`32027` |FLAC |FLAC audio compression filter in HDF5|
-|`32028` |SPERR |SPERR is a lossy scientific (floating-point) data compressor that produces one of the best rate-distortion curves|
-|`32029` |TERSE/PROLIX |A lossless and fast compression of the diffraction data|
-|`32030` |FFMPEG |A lossy compression filter based on ffmpeg video library|
-|`32031` |JPEG2000 | A compression filter for lossy and lossless coding|
+The **Canonical Name** column is the string identifier used by `H5Z_class3_t` plugins. Entries marked _(proposed)_ are pending confirmation by the plugin maintainer; see [Canonical Names](#canonical-names-h5z_class3_t-plugin-class) and the [tracking issue](https://github.com/HDFGroup/hdf5_plugins/issues/255).
+
+| Plugin Identifier | Canonical Name | For Filter | Short Description|
+|--------|--------|----------------|---------------------|
+|`257` |`hzip` _(proposed)_ |hzip |hzip compression used in Silo|
+|`258` |`fpzip-legacy` _(proposed)_ |fpzip |Duplicate of plugin `32014`|
+|`305` |`lzo` _(proposed)_ |LZO |LZO lossless compression used by PyTables|
+|`307` |`bzip2` _(proposed)_ |BZIP2 |BZIP2 lossless compression used by PyTables|
+|`32000` |`lzf` _(proposed)_ |LZF |LZF lossless compression used by the h5py package|
+|`32001` |`blosc` _(proposed)_ |BLOSC |Blosc lossless compression used by PyTables|
+|`32002` |`mafisc` _(proposed)_ |MAFISC |Modified LZMA compression filter, MAFISC (Multidimensional Adaptive Filtering Improved Scientific data Compression)|
+|`32003` |`snappy` _(proposed)_ |Snappy |Snappy lossless compression|
+|`32004` |`lz4` _(proposed)_ |LZ4 |LZ4 fast lossless compression algorithm|
+|`32005` |`apax` _(proposed)_ |APAX |Samplify’s APAX Numerical Encoding Technology|
+|`32006` |`cbf` _(proposed)_ |CBF |All imgCIF/CBF compressions and decompressions, including Canonical, Packed, Packed Version 2, Byte Offset and Nibble Offset|
+|`32007` |`jpeg-xr` _(proposed)_ |JPEG-XR |Enables images to be compressed/decompressed with JPEG-XR compression|
+|`32008` |`bitshuffle` _(proposed)_ |bitshuffle |Extreme version of shuffle filter that shuffles data at bit level instead of byte level|
+|`32009` |`spdp` _(proposed)_ |SPDP |SPDP fast lossless compression algorithm for single- and double-precision floating-point data|
+|`32010` |`lpc-rice` _(proposed)_ |LPC-Rice |LPC-Rice multi-threaded lossless compression|
+|`32011` |`ccsds-123` _(proposed)_ |CCSDS-123 |ESA CCSDS-123 multi-threaded compression filter|
+|`32012` |`jpeg-ls` _(proposed)_ |JPEG-LS |CharLS JPEG-LS multi-threaded compression filter|
+|`32013` |`zfp` _(proposed)_ |zfp |Lossy & lossless compression of floating point and integer datasets to meet rate, accuracy, and/or precision targets.|
+|`32014` |`fpzip` _(proposed)_ |fpzip |Fast and Efficient Lossy or Lossless Compressor for Floating-Point Data|
+|`32015` |`zstd` _(proposed)_ |Zstandard |Real-time compression algorithm with wide range of compression / speed trade-off and fast decoder|
+|`32016` |`b3d` _(proposed)_ |B³D |GPU based image compression method developed for light-microscopy applications|
+|`32017` |`sz` _(proposed)_ |SZ |An error-bounded lossy compressor for scientific floating-point data|
+|`32018` |`fcidecomp` _(proposed)_ |FCIDECOMP |EUMETSAT CharLS compression filter for use with netCDF|
+|`32019` |`jpeg` _(proposed)_ |JPEG |Jpeg compression filter|
+|`32020` |`vbz` _(proposed)_ |VBZ |Compression filter for raw dna signal data used by Oxford Nanopore|
+|`32021` |`fapec` _(proposed)_ |FAPEC | Versatile and efficient data compressor supporting many kinds of data and using an outlier-resilient entropy coder|
+|`32022` |`bitgroom` _(proposed)_ |BitGroom |The BitGroom quantization algorithm|
+|`32023` |`granular-bitround` _(proposed)_ |Granular BitRound (GBR) |The GBR quantization algorithm is a significant improvement to the BitGroom filter|
+|`32024` |`sz3` _(proposed)_ |SZ3 |A modular error-bounded lossy compression framework for scientific datasets|
+|`32025` |`delta-rice` _(proposed)_ |Delta-Rice |Lossless compression algorithm optimized for digitized analog signals based on delta encoding and rice coding|
+|`32026` |`blosc2` _(proposed)_ |BLOSC2 |The recent new-generation version of the Blosc compression library|
+|`32027` |`flac` _(proposed)_ |FLAC |FLAC audio compression filter in HDF5|
+|`32028` |`sperr` _(proposed)_ |SPERR |SPERR is a lossy scientific (floating-point) data compressor that produces one of the best rate-distortion curves|
+|`32029` |`terse-prolix` _(proposed)_ |TERSE/PROLIX |A lossless and fast compression of the diffraction data|
+|`32030` |`ffmpeg` _(proposed)_ |FFMPEG |A lossy compression filter based on ffmpeg video library|
+|`32031` |`jpeg2000` _(proposed)_ |JPEG2000 | A compression filter for lossy and lossless coding|
> [!NOTE]
> Please contact the maintainer of a filter plugin for help with the plugin or its filter in the HDF5 library.
+## Canonical Names (`H5Z_class3_t` plugin class)
+
+Starting with the v3 filter plugin class (`H5Z_class3_t`), introduced in HDF5 2.x, every registered filter has a **canonical name**: a short, stable string identifier used by callers, tools, and the on-disk format.
+
+### Where the canonical name appears
+
+* **In the plugin source.** An `H5Z_class3_t` plugin sets its `name` to the canonical name.
+* **In the file.** When an HDF5 library that supports `H5Z_class3_t` adds a filter to a dataset's pipeline, it writes the canonical name into the filter-pipeline message (`H5O_PLINE`), so tools like `h5dump` can identify the filter even when the plugin shared library is not installed.
+* **In the API.** The forthcoming `H5Pappend_filter("canonical_name", "params")` interface accepts the canonical name to identify the filter, and accepts a TOML inline table parameter string for typed configuration. (Numeric filter IDs continue to work via the existing `H5Pset_filter` interface.)
+* **In CLI tools.** `h5repack`, `h5dump`, and other tools display the canonical name when printing filter information.
+
+### Syntactic rules
+
+* Non-NULL, non-empty.
+* At most 255 bytes.
+* Drawn from the character class `[A-Za-z0-9_.-]`.
+* Matched case-sensitively.
+
+Registrations that violate these rules are rejected by `H5Zregister()` with `H5E_BADVALUE`.
+
+### Allocation
+
+The HDF Group assigns a canonical name alongside the numeric `id` at filter-registration time. First-registered wins, exactly as for numeric IDs: if two plugins claim the same canonical name in one process, the second `H5Zregister()` call is rejected with `H5E_CANTREGISTER`. Coordination through this registry is the only guarantee that, for example, `"zfp"` means the same plugin on every system.
+
+### Self-namespacing (non-normative)
+
+Third-party plugins that have not gone through HDF Group filter registration should self-namespace their canonical names (for example, `org.example.fastlz`) to make accidental collisions vanishingly unlikely. Coordinated registration through The HDF Group remains the recommended path for plugins that want a short, bare name.
+
+### Updating an existing registration for `H5Z_class3_t`
+
+Existing filter plugins continue to work unchanged with HDF5 2.x; the canonical name only becomes load-bearing when a plugin opts into the new `H5Z_class3_t` class. Maintainers of currently registered plugins should:
+
+1. Review the proposed canonical name in the table above for your filter ID.
+2. Confirm or propose a correction by replying on the [tracking issue](https://github.com/HDFGroup/hdf5_plugins/issues/255) or contacting the HDF Group [Helpdesk](mailto:help@hdfgroup.org). Confirmations replace _(proposed)_ in the table.
+3. When porting the plugin to `H5Z_class3_t`, set the `name` field to the registered canonical name byte-identically.
+
+See the HDF5 RFC on string-configured filters (RFC-HDFG-2026-001) for the full v3 design.
+
## Information about Registered Filter Plugins
### hzip