Descriptions for what some EA mean

General information
The EAs everyone should be aware of
Native file:// EAs
Image related EAs
Audio related EAs
Video related EAs
EA which relate to branch filesystems
RPM EA
Miscellaneous EA which are very handy for specific use cases

General information

The below tables do not take into account all EA for the system. They are designed as a guide to the libferris 1.1.40+ EA. Once an EA is in the system it rarely changes so these tables should be suitable for future versions of libferris.

Some EA generated from libextractor, native kernel EA and RDF sources are impossible to fully enumerate here in a timely manner. Also when you mount a relational database or XML file/database attributes are created to export information of interest. For example a relational database when mounted shows its rows as files and its columns as EA on those files. One should keep this in mind and consider the tables as a reference to only some of the EAs in the system.

Another section that is only briefly mentioned is the emblem EAs. This is because each user is expected to have their own emblem collection with their own partial ordering over their emblems. See the ADCS03 paper in the papers section of the site for a starting guide to emblems and one of their considered uses.

The EAs everyone should be aware of

This table describes important EA.

Important EA
EA name	description
as-rdf	All the EA for the file presented as an RDF/XML document
as-xml	All the EA for the file presented as an XML document
as-text	A plain text representation of the file. May loose formatting information.
content	The file's contents.
url	The file's URL. eg. file://tmp/foobar.tar
path	Path for this file. eg. /tmp/foobar.tar
name-extension	File's extension. eg. tar
atime	Time of last access. In seconds since UNIX epoch (1/Jan/1970)
atime-ctime	ctime(3) formated string showing the atime EA
atime-display	atime EA shown in a user selectable presentation format
atime-day-granularity	atime EA rounded down to nearest day
atime-month-granularity	atime EA rounded down to nearest month
atime-year-granularity	atime EA rounded down to nearest year
ctime	Same collection of EA as for atime
ferris-current-time	Same collection of EA as for atime
mtime	Same collection of EA as for atime
attribute-count	Total number of EAs for this file
ea-names	A list of the names of all EA for this file.
recommended-ea	The names of EA which should be interesting to the user for this file.
recommended-ea-short	A shortened version of recommended-ea
recommended-ea-union	The union of recommended-ea for all files/dirs in a directory.
treeicon	The URL of an image that is appropriate for this file.
emblem:list	A complete listing of all emblems as a comma seperated list
emblem:list-ui	A listing of all important emblems as a comma seperated list
emblem:x-mtime	The last time data about the "x" emblem was changed. This also has the "-ctime", "-display" EA for accessing this time in a formatted manner.
emblem:has-x	Is this file associated with emblem "x"
emblem:has-fuzzy-x	Based on supervised machine learning should this file be associated with emblem "x"
is-active-view	Will this directory update itself to reflect changes made by other apps
is-animation-object	Is the MIME major type animation
is-audio-object	Is the MIME major type audio
is-image-object	Is the MIME major type image
is-source-object	Is this file source code
is-dir	Underlying kernel object is a directory
is-file	Underlying kernel object is a file
language-human	What is the human language for this file. eg. english
mimetype	MIME type of the file perhaps based on quick guessing
mimetype-from-content	MIME type of the file definately based on inspecting file bytes.
is-native	Using kernel based filesystem (a file:// URL)
is-remote	Is this file remote to this machine
size	Size of the file
size-human-readable	Size of the file in human readable format (similar to ls -lh)
md2	Checksums calculated from the file's byte content when the EA are read.
mdc2	Checksums calculated from the file's byte content when the EA are read.
md5	Checksums calculated from the file's byte content when the EA are read.
sha1	Checksums calculated from the file's byte content when the EA are read.

Native file:// EAs

This table describes various EA which are likely to be only found for file:// URLs. For file:// URLs there is also a "dontfollow-" prefixed version of some EA which present the values found from a lstat(2) call. By default the stat(2) call values are shown which means that the EA values for link files are for the link target not the link itself.

native file:// metadata
EA name	description
device	st_dev from stat(2)
device-type	st_rdev from stat(2)
filesystem-filetype	string describing the type of this file.
force-passive-view	Has the user elected not to monitor this directory for changes
fs-available-block-count	f_bavail from statfs(2)
fs-block-count	f_blocks from statfs(2)
fs-block-size	f_bsize from statfs(2)
fs-file-name-length-maximum	f_namelen from statfs(2)
fs-file-nodes-free	f_ffree from statfs(2)
fs-file-nodes-total	f_files from statfs(2)
fs-free-block-count	f_bfree from statfs(2)
fs-id	f_fsid from statfs(2)
fs-name	Name of filesystem this file is on. eg. ext2
fs-type	f_type from statfs(2)
group-executable	File mode has g+x
group-readable	File mode has g+r
group-writable	File mode has g+w
group-owner-name	Name of group owning file
group-owner-number	Number of group owning file
hard-link-count	st_nlink from stat(2)
has-holes	Does the file contain holes?
has-subcontexts-guess	A quick guess if this object has children
has-valid-signature	Is there a valid digital signature for this file
inode	INode for this file
is-link	Underlying kernel object is a link
is-special	Underlying kernel object is a special object
mode	st_mode from stat(2)
protection-ls	mode EA formatted for ls(1) display
other-executable	File mode has o+x
other-readable	File mode has o+r
other-writable	File mode has o+w
readable	Can the user reading this EA read the file?
writable	Can the user reading this EA write to the file?
realpath	For links returns the realpath(3) string
runable	Can the user reading this EA run this file?
deletable	Can the user reading this EA delete this file? eg. A directory with +wx permissions set for other implicitly allows all users to delete any file in that directory.
user-executable	File mode has u+x
user-readable	File mode has u+r
user-writable	File mode has u+w
user-owner-name	Name of owner of this file
user-owner-number	Number for owner of this file
block-count	Number of disk blocks occupied by this file
block-size	Size of the disk blocks used by this file

Image related EAs

These will be likely available for many image formats depending on what support for images your build of libferris was created with. Note that some EAs such as the EXIF and XMP generated EAs are not described here but have similar names to the attributes of the underlying specification where spaces and underscores are replaced with "-".

Image EA
EA name	description
aspect-ratio	Image data's width to height ratio
depth	Number of bits per pixel
depth-per-color	Number of bits per colour
gamma	Gamma adjustment for this image
has-alpha	true if there is an alpha channel
height	Height of the image
width	Width of the image
rgba-32bpp	Decoded image data in RGBA 32 bit per pixel format
exif:has-thumbnail	Is there an EXIF thumbnal in this image
exif:thumbnail-update	Echoing 1 into this will recreate the EXIF thumbnail
exif:thumbnail-height	EXIF thumbnal height
exif:thumbnail-width	EXIF thumbnal width
exif:thumbnail-rgba-32bpp	Decoded thumbnail image. Same format as rgba-32bpp
exif:...	All EXIF tag metadata is exported with logical EA names
been-downloaded	Has this image been downloaded from the digital camera already
deletable	Can we delete this image from the digital camera.

Audio related EAs

These will be available on some or all of your audio files providing interesting metadata about them.

Audio EA
EA name	description
a52-bit-rate	bit rate of an ac3/a52 audio stream. The a52-* information is also provided for mpeg2 files that have such audio embedded in them.
a52-sample-rate
a52-has-base	Is there a base channel
a52-frame-length
a52-channels	Number of audio channels
a52-channels-front	Number of 'front' audio channels
a52-channels-rear
title	ID3: track title
artist	ID3: artist for track
album	ID3: Name of album containing track
year	ID3: Year the album/single containing this track was released
track	ID3: Number of this track from its album. eg. 7

Video related EAs

These will be available on some or all of your video files providing interesting metadata about them.

Video EA
EA name	description
pgmpipe	A stream of YUV images containing the decoded images from the video file
width	Width of the video file
height	Height of the video file
frame-count	number of video frames in file
duration	Duration of video in seconds
aspect-ratio	Ratio of width to height of how video should be shown
letterbox	Is video letterboxed

EA which relate to branch filesystems

Branch filesystems present information about a file via a virtual filesystem. For example for a digitally signed file the people who have signed the file, when they signed it and if the signature is valid are all expressed via a branch filesystem.

EA which relate to branch filesystems
EA name	description
associated-branches	List of all "branchfs-" EA for this file
associated-branches-url	URL for a filesystem showing all "branchfs-" EA for this file
branchfs-attributes	URL which will show this file's EA as directory containing files
branchfs-medallions	URL which will show this file's emblems as a directory containing files
branchfs-parents	URL which will show All the parents of this file
branchfs-signatures	URL which will show the people who have signed this file and when

RPM EA

These EAs are available on RPM based Linux distributions. They provide information about each file that is taken from the rpm database on the machine. See rpm(8) for more information.

RPM EA
EA name	description
rpm-info-url
rpm-is-config
rpm-is-doc
rpm-is-ghost
rpm-is-license
rpm-is-pubkey
rpm-is-readme
rpm-package	RPM package which installed this file
rpm-release	release of rpm-package that installed this file
rpm-verify-device
rpm-verify-group
rpm-verify-md5	true if the file has not been changed since it was installed.
rpm-verify-mode
rpm-verify-mtime
rpm-verify-owner
rpm-verify-size
rpm-version

Miscellaneous EA which are very handy for specific use cases

These have been added to the system over time usually to solve specific problems.

Miscellaneous EA
EA name	description
parent-name	Name of the parent dir. eg. for /tmp/foobar.tar, parent-name=tmp
download-if-mtime-since	Before reading a document from HTTP/FTP a time can be written to this EA and an exception will be thrown if the remove document has not been modified since the written time. Also has the same collection of EA as for atime
size-cdrom-count	Number of 700Mb CDROMs required for this file
size-dvd-count	Number of 4.4Gb DVDs required for this file
recursive-subcontext-*	The "recursive-" prefix EA return similar information for a whole tree. They can be slow to read as a full traversal of all children may be required.
subcontext-*	The "subcontext-" EA return information about direct children.

eadescriptions