use CodecPrivate instead of Private Data

We already have a name for the field, no need for an extra indirection.

codec_specs.md

@@ -67,8 +67,7 @@ which **MUST** be stored within the `CodecPrivate` element. When the Initializat
 within a track, then that updated Initialization data **MUST** be written into the `CodecState` element
 of the first `Cluster` to require it. If the encoding does not require any form of Initialization,
 then `none` **MUST** be used to define the Initialization and the `CodecPrivate` element
-**SHOULD NOT** be written and **MUST** be ignored. Data that is defined Initialization to be
-stored in the `CodecPrivate` element is known as `Private Data`.
+**SHOULD NOT** be written and **MUST** be ignored.
 
 ### Codec BlockAdditions
 
@@ -192,7 +191,7 @@ Description: FFV1 is a lossless intra-frame video encoding format designed to ef
 Compared to uncompressed video, FFV1 offers storage compression, frame fixity, and self-description,
 which makes FFV1 useful as a preservation or intermediate video format. [Draft FFV1 Specification](https://datatracker.ietf.org/doc/draft-ietf-cellar-ffv1/)
 
-Initialization: For FFV1 versions 0 or 1, `Private Data` **SHOULD NOT** be written. For FFV1 version 3 or greater, the `Private Data` **MUST** contain the FFV1 Configuration Record structure, as defined in https://tools.ietf.org/html/draft-ietf-cellar-ffv1-04#section-4.2, and no other data.
+Initialization: For FFV1 versions 0 or 1, `CodecPrivate` **SHOULD NOT** be written. For FFV1 version 3 or greater, the `CodecPrivate` **MUST** contain the FFV1 Configuration Record structure, as defined in https://tools.ietf.org/html/draft-ietf-cellar-ffv1-04#section-4.2, and no other data.
 
 ### V_MPEGH/ISO/HEVC
 
@@ -202,7 +201,7 @@ Codec Name: HEVC/H.265
 
 Description: Individual pictures (which could be a frame, a field, or 2 fields having the same timestamp) of HEVC/H.265 stored as described in [@!ISO.14496-15].
 
-Initialization: The `Private Data` contains a `HEVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
+Initialization: The `CodecPrivate` contains a `HEVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
 
 ### V_MPEGI/ISO/VVC
 
@@ -212,7 +211,7 @@ Codec Name: VVC/H.266
 
 Description: Individual pictures (which could be a frame, a field, or 2 fields having the same timestamp) of VVC/H.266 stored as described in [@!ISO.14496-15].
 
-Initialization: The `Private Data` contains a `VVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
+Initialization: The `CodecPrivate` contains a `VVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
 
 ### V_MPEG1
 
@@ -246,7 +245,7 @@ Codec Name: AVC/H.264
 
 Description: Individual pictures (which could be a frame, a field, or 2 fields having the same timestamp) of AVC/H.264 stored as described in [@!ISO.14496-15].
 
-Initialization: The `Private Data` contains a `AVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
+Initialization: The `CodecPrivate` contains a `AVCDecoderConfigurationRecord` structure, as defined in [@!ISO.14496-15].
 For legacy reasons, because `Block Additional Mappings` are preferred; see (#block-addition-mappings),
 the `AVCDecoderConfigurationRecord` structure **MAY** be followed by an extension block beginning
 with a 4-byte extension block size field in big-endian byte order which is the size of the extension block
@@ -311,7 +310,7 @@ the extra private bytes, as [defined by Microsoft](https://msdn.microsoft.com/en
 The data are stored in little-endian format (like on IA32 machines). Where is the Huffman table stored
 in HuffYUV, not AVISTREAMINFO ??? And the FourCC, not in AVISTREAMINFO.fccHandler ???
 
-Initialization: `Private Data` contains the VCM structure BITMAPINFOHEADER including the extra private bytes,
+Initialization: `CodecPrivate` contains the VCM structure BITMAPINFOHEADER including the extra private bytes,
 as defined by Microsoft in https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx.
 
 Citation: https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376(v=vs.85).aspx
@@ -324,7 +323,7 @@ Codec Name: Video taken from QuickTime files
 
 Description: Several codecs as stored in QuickTime (e.g., Sorenson or Cinepak).
 
-Initialization: The `Private Data` contains all additional data that is stored in the 'stsd' (sample description) atom
+Initialization: The `CodecPrivate` contains all additional data that is stored in the 'stsd' (sample description) atom
 in the QuickTime file **after** the mandatory video descriptor structure
 (starting with the size and FourCC fields). For an explanation of the QuickTime file format read [QuickTime File Format Specification](https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFPreface/qtffPreface.html).
 
@@ -334,7 +333,7 @@ Codec ID: V_PRORES
 
 Codec Name: Apple ProRes
 
-Initialization: The `Private Data` contains the FourCC as found in MP4 movies:
+Initialization: The `CodecPrivate` contains the FourCC as found in MP4 movies:
 
 *   ap4x: ProRes 4444 XQ
 
@@ -362,7 +361,7 @@ Codec Name: RealVideo 1.0 aka RealVideo 5
 
 Description: Individual slices from the Real container are combined into a single frame.
 
-Initialization: The `Private Data` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
+Initialization: The `CodecPrivate` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### V_REAL/RV20
 
@@ -372,7 +371,7 @@ Codec Name: RealVideo G2 and RealVideo G2+SVT
 
 Description: Individual slices from the Real container are combined into a single frame.
 
-Initialization: The `Private Data` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
+Initialization: The `CodecPrivate` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### V_REAL/RV30
 
@@ -382,7 +381,7 @@ Codec Name: RealVideo 8
 
 Description: Individual slices from the Real container are combined into a single frame.
 
-Initialization: The `Private Data` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
+Initialization: The `CodecPrivate` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### V_REAL/RV40
 
@@ -392,15 +391,15 @@ Codec Name: rv40 : RealVideo 9
 
 Description: Individual slices from the Real container are combined into a single frame.
 
-Initialization: The `Private Data` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
+Initialization: The `CodecPrivate` contains a `real_video_props_t` structure in big-endian byte order as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### V_THEORA
 
 Codec ID: V_THEORA
 
 Codec Name: Theora
 
-Initialization: The `Private Data` contains the first three Theora packets in order. The lengths of the packets precedes them. The actual layout is:
+Initialization: The `CodecPrivate` contains the first three Theora packets in order. The lengths of the packets precedes them. The actual layout is:
 
 * Byte 1: number of distinct packets `#p` minus one inside the CodecPrivate block. This **MUST** be "2" for current (as of 2016-07-08) Theora headers.
 
@@ -596,7 +595,7 @@ Codec ID: A_ALAC
 
 Codec Name: ALAC (Apple Lossless Audio Codec)
 
-Initialization: The `Private Data` contains ALAC's magic cookie (both the codec specific configuration as well as the optional channel layout information).
+Initialization: The `CodecPrivate` contains ALAC's magic cookie (both the codec specific configuration as well as the optional channel layout information).
 Its format is described in [ALAC's official source code](http://alac.macosforge.org/trac/browser/trunk/ALACMagicCookieDescription.txt).
 
 ### A_ATRAC/AT1
@@ -654,7 +653,7 @@ Codec ID: A_FLAC
 
 Codec Name: [FLAC (Free Lossless Audio Codec)](http://flac.sourceforge.net/)
 
-Initialization: The `Private Data` contains all the header/metadata packets before the first data packet.
+Initialization: The `CodecPrivate` contains all the header/metadata packets before the first data packet.
 These include the first header packet containing only the word `fLaC` as well as all metadata packets.
 
 ### A_MPC
@@ -704,7 +703,7 @@ Codec Name: Microsoft Audio Codec Manager (ACM)
 
 Description: The data are stored in little-endian format (like on IA32 machines).
 
-Initialization: The `Private Data` contains the [@!WAVEFORMATEX] structure including the extra format information bytes.
+Initialization: The `CodecPrivate` contains the [@!WAVEFORMATEX] structure including the extra format information bytes.
 The structure is stored without packing or padding bytes.
 A `WORD` corresponds to a signed 2 octets integer, `DWORD` corresponds to a signed 4 octets integer.
 The extra format information are appended after the WAVEFORMATEX octets.
@@ -715,7 +714,7 @@ Codec ID: A_REAL/14_4
 
 Codec Name: Real Audio 1
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_REAL/28_8
@@ -724,7 +723,7 @@ Codec ID: A_REAL/28_8
 
 Codec Name: Real Audio 2
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_REAL/ATRC
@@ -733,7 +732,7 @@ Codec ID: A_REAL/ATRC
 
 Codec Name: Sony Atrac3 Codec
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_REAL/COOK
@@ -742,7 +741,7 @@ Codec ID: A_REAL/COOK
 
 Codec Name: Real Audio Cook Codec (codename: Gecko)
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_REAL/RALF
@@ -751,7 +750,7 @@ Codec ID: A_REAL/RALF
 
 Codec Name: Real Audio Lossless Format
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_REAL/SIPR
@@ -760,7 +759,7 @@ Codec ID: A_REAL/SIPR
 
 Codec Name: Sipro Voice Codec
 
-Initialization: The `Private Data` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
+Initialization: The `CodecPrivate` contains either the "real_audio_v4_props_t" or the "real_audio_v5_props_t" structure
 (differentiated by their "version" field; big-endian byte order) as found in [librmff](https://github.com/mbunkus/mkvtoolnix/blob/master/lib/librmff/librmff.h).
 
 ### A_OPUS
@@ -826,7 +825,7 @@ Codec Name: Audio taken from QuickTime files
 
 Description: Several codecs as stored in QuickTime (e.g., QDesign Music v1 or v2).
 
-Initialization: The `Private Data` contains all additional data that is stored in the 'stsd' (sample description) atom
+Initialization: The `CodecPrivate` contains all additional data that is stored in the 'stsd' (sample description) atom
 in the QuickTime file **after** the mandatory sound descriptor structure (starting with the size and FourCC fields).
 For an explanation of the QuickTime file format read [QuickTime File Format Specification](https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFPreface/qtffPreface.html).
 
@@ -838,7 +837,7 @@ Codec Name: QDesign Music
 
 Description:
 
-Initialization: The `Private Data` contains all additional data that is stored in the 'stsd' (sample description) atom
+Initialization: The `CodecPrivate` contains all additional data that is stored in the 'stsd' (sample description) atom
 in the QuickTime file **after** the mandatory sound descriptor structure (starting with the size and FourCC fields).
 For an explanation of the QuickTime file format read [QuickTime File Format Specification](https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFPreface/qtffPreface.html).
 
@@ -852,7 +851,7 @@ Codec Name: QDesign Music v2
 
 Description:
 
-Initialization: The `Private Data` contains all additional data that is stored in the 'stsd' (sample description) atom
+Initialization: The `CodecPrivate` contains all additional data that is stored in the 'stsd' (sample description) atom
 in the QuickTime file **after** the mandatory sound descriptor structure (starting with the size and FourCC fields).
 For an explanation of the QuickTime file format read [QuickTime File Format Specification](https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFPreface/qtffPreface.html).
 
@@ -875,7 +874,7 @@ Codec ID: A_VORBIS
 
 Codec Name: Vorbis
 
-Initialization: The `Private Data` contains the first three Vorbis packet in order. The lengths of the packets precedes them. The actual layout is:
+Initialization: The `CodecPrivate` contains the first three Vorbis packet in order. The lengths of the packets precedes them. The actual layout is:
 - Byte 1: number of distinct packets `#p` minus one inside the CodecPrivate block.
   This **MUST** be "2" for current (as of 2016-07-08) Vorbis headers.
 - Bytes 2..n: lengths of the first `#p` packets, coded in Xiph-style lacing.