$ fq -n _registry.groups.probe
[
  "adts",
  "apple_bookmark",
  "ar",
  "avi",
  "avro_ocf",
  "bitcoin_blkdat",
  "bplist",
  "bzip2",
  "elf",
  "flac",
  "gif",
  "gzip",
  "jpeg",
  "macho",
  "macho_fat",
  "matroska",
  "mp4",
  "ogg",
  "pcap",
  "pcapng",
  "png",
  "tar",
  "tiff",
  "tzif",
  "wasm",
  "webp",
  "zip",
  "mp3",
  "mpeg_ts",
  "wav",
  "json",
  "jsonl",
  "toml",
  "xml",
  "yaml"
]
$ fq --help formats
aac_frame            Advanced Audio Coding frame
adts                 Audio Data Transport Stream
adts_frame           Audio Data Transport Stream frame
amf0                 Action Message Format 0
apev2                APEv2 metadata tag
apple_bookmark       Apple BookmarkData
ar                   Unix archive
asn1_ber             ASN1 BER (basic encoding rules, also CER and DER)
av1_ccr              AV1 Codec Configuration Record
av1_frame            AV1 frame
av1_obu              AV1 Open Bitstream Unit
avc_annexb           H.264/AVC Annex B
avc_au               H.264/AVC Access Unit
avc_dcr              H.264/AVC Decoder Configuration Record
avc_nalu             H.264/AVC Network Access Layer Unit
avc_pps              H.264/AVC Picture Parameter Set
avc_sei              H.264/AVC Supplemental Enhancement Information
avc_sps              H.264/AVC Sequence Parameter Set
avi                  Audio Video Interleaved
avro_ocf             Avro object container file
bencode              BitTorrent bencoding
bitcoin_blkdat       Bitcoin blk.dat
bitcoin_block        Bitcoin block
bitcoin_script       Bitcoin script
bitcoin_transaction  Bitcoin transaction
bits                 Raw bits
bplist               Apple Binary Property List
bsd_loopback_frame   BSD loopback frame
bson                 Binary JSON
bytes                Raw bytes
bzip2                bzip2 compression
cbor                 Concise Binary Object Representation
csv                  Comma separated values
dns                  DNS packet
dns_tcp              DNS packet (TCP)
elf                  Executable and Linkable Format
ether8023_frame      Ethernet 802.3 frame
exif                 Exchangeable Image File Format
fairplay_spc         FairPlay Server Playback Context
flac                 Free Lossless Audio Codec file
flac_frame           FLAC frame
flac_metadatablock   FLAC metadatablock
flac_metadatablocks  FLAC metadatablocks
flac_picture         FLAC metadatablock picture
flac_streaminfo      FLAC streaminfo
gif                  Graphics Interchange Format
gzip                 gzip compression
hevc_annexb          H.265/HEVC Annex B
hevc_au              H.265/HEVC Access Unit
hevc_dcr             H.265/HEVC Decoder Configuration Record
hevc_nalu            H.265/HEVC Network Access Layer Unit
hevc_pps             H.265/HEVC Picture Parameter Set
hevc_sps             H.265/HEVC Sequence Parameter Set
hevc_vps             H.265/HEVC Video Parameter Set
html                 HyperText Markup Language
icc_profile          International Color Consortium profile
icmp                 Internet Control Message Protocol
icmpv6               Internet Control Message Protocol v6
id3v1                ID3v1 metadata
id3v11               ID3v1.1 metadata
id3v2                ID3v2 metadata
ipv4_packet          Internet protocol v4 packet
ipv6_packet          Internet protocol v6 packet
jpeg                 Joint Photographic Experts Group file
json                 JavaScript Object Notation
jsonl                JavaScript Object Notation Lines
macho                Mach-O macOS executable
macho_fat            Fat Mach-O macOS executable (multi-architecture)
markdown             Markdown
matroska             Matroska file
mp3                  MP3 file
mp3_frame            MPEG audio layer 3 frame
mp3_frame_tags       MP3 frame info/xing tags
mp4                  ISOBMFF, QuickTime and similar
mpeg_asc             MPEG-4 Audio Specific Config
mpeg_es              MPEG Elementary Stream
mpeg_pes             MPEG Packetized elementary stream
mpeg_pes_packet      MPEG Packetized elementary stream packet
mpeg_spu             Sub Picture Unit (DVD subtitle)
mpeg_ts              MPEG Transport Stream
msgpack              MessagePack
ogg                  OGG file
ogg_page             OGG page
opus_packet          Opus packet
pcap                 PCAP packet capture
pcapng               PCAPNG packet capture
png                  Portable Network Graphics file
prores_frame         Apple ProRes frame
protobuf             Protobuf
protobuf_widevine    Widevine protobuf
pssh_playready       PlayReady PSSH
rtmp                 Real-Time Messaging Protocol
sll2_packet          Linux cooked capture encapsulation v2
sll_packet           Linux cooked capture encapsulation
tar                  Tar archive
tcp_segment          Transmission control protocol segment
tiff                 Tag Image File Format
toml                 Tom's Obvious, Minimal Language
tzif                 Time Zone Information Format
udp_datagram         User datagram protocol
vorbis_comment       Vorbis comment
vorbis_packet        Vorbis packet
vp8_frame            VP8 frame
vp9_cfm              VP9 Codec Feature Metadata
vp9_frame            VP9 frame
vpx_ccr              VPX Codec Configuration Record
wasm                 WebAssembly Binary Format
wav                  WAV file
webp                 WebP image
xml                  Extensible Markup Language
yaml                 YAML Ain't Markup Language
zip                  ZIP archive