View source for EA DATA. SF

{{FormatInfo
|formattype=electronic
|subcat=Metadata
|extensions={{ext| sf}}
}}
'''EA DATA. SF''' is the filename of a special hidden file that may be present on [[FAT]] filesystems used by OS/2. It contains [[OS/2 extended attributes|extended file attributes]] that are supported by [[HPFS]] but not by FAT.

== Format details ==
The EA DATA file is highly "fragmented", in such a way as to keep a user file's attributes physically close to its data.

Accurately decoding an EA DATA file can only be done in the context of the [[FAT]] filesystem that contains it. For a user file that has extended attributes, its FAT directory entry contains a special nonzero identifier at offset 20 (from the beginning of the filename field). These identifiers refer to sections of the EA DATA file.

== Specifications ==
* [https://www.tavi.co.uk/os2pages/eadata.html Implementation of extended attributes on the FAT file system], section titled "Notes on the format of the EA datafile"
** [https://archive.org/details/minerva2 Minerva II] → [https://archive.org/download/minerva2/minerva2.zip/minerva2%2FOS2%2FEADATA.ARJ OS2/EADATA.ARJ] - Same information

== Sample files ==
* Often found on OS/2 floppy disk images. For example, see [[LoadDskF/SaveDskF#Sample files]].

== Links ==
* [[Wikipedia: File Allocation Table#Extended Attributes]]
* [http://www.edm2.com/index.php/The_Fundamentals_of_Extended_Attributes EDM2: The Fundamentals of Extended Attributes]
* [http://www.edm2.com/index.php/CPGuide_-_Extended_Attributes EDM2: CPGuide - Extended Attributes]
* [https://patents.google.com/patent/US5367671 US patent 5367671]: System for accessing extended object attribute (EA) data through file name or EA handle linkages in path tables

[[Category:File formats with extension .sf]]
[[Category:Filesystem]]
[[Category:OS/2]]
[[Category:File formats with a distinctive filename]]