EPWING

File Format
Name	EPWING
Ontology	Electronic File Formats Electronic Publishing formats EPWING
Extension(s)	(none)
Wikidata ID	Q11197749
Compression	none
Released	1987

Majority of the links/citations are in Japanese.

Electronic Publishing-WING or EPWING, is a standardized format for electronic reference materials, typically dictionaries that were distributed on CD-ROM for PCs. Electronic dictionaries in general were also popular in East Asia.

The format itself is largely uncompressed, taking advantage of larger storage capacities CD-ROMs offered over hard disks, and what was the largely unjustifiable cost of storing duplicate data, as well as older PC hardware that have other resource limitations such as slower CPU or less RAM/memory capacities.

Content structure

EPWING files generally do not have any extensions, with the exception of when they are compressed using the likes of EBZip. Below is a rough outline describing what it would look like:

 ├── (top directory)
 │   ├── Catalogs
 │   └── (e-book name)
 │       ├── DATA
 │       │   └── HONMON
 │       ├── GAIJI
 │       │   ├── GAI16F
 │       │   ├── GAI16H
 │       │   ├── GAI24F
 │       │   └── GAI24H
 │       └── MOVIE
 │           ├── 0000115

There are many exceptions to this layout, for instance, the,

• File named "Catalogs" may be in all caps or all lower-case,
• "HONMON" may include one or more of similar names, like "HONMON2" or "HONMONG", etc,
• "MOVIE" path may or may not exist, depending on the digitized referencing material, subsequently the filenames may also vary.

History

EPWING was a consortium of five members; Iwanami Shoten, Dai Nippon Printing, Toppan Printing, Fujitsu and Sony, produced the Electronic Book (EB) extension based on WING standard in circa 1991, with the aim to promote electronic publications in a common format, and to standardize WING onto ISO 9660 (the logical format for CD-ROMs), establishing the first edition (V1) of the EPWING convention.

Modern use and alternatives

The format is still in use by users who have been accustomed to the software, however it is considered to be a niche crowd when compared to StarDict. It might be better known through the use of EB library's EBZip utility, which offers lossless, "transparent-like" compression that seamlessly works with modern EPWING reader software, without the need to decompress first before using the data.

As the format was intended for digitized hardcopies of published books, it is possible to create your own electronic referencing materials in EPWING format. A common example is Wikipedia where the user runs either a pre-made FreePWING or FreeUWING, the latter FreeUWING, being a variant that uses UTF-8 extensions which the FreePWING lacked, as Unicode format wasn't standardized nor widespread.

The format is also seen its use as a conversion to yomitan/yomichan web browser extension/add-on, notably via FooSoft's zero-epwing that aims to convert specific electronic EPWING formatted dictionaries into a JSON format suitable for on-screen pop-up translation. Aedict also supports one very specific EPWING dictionary, Daijirin with the developer citing the same niche format issues.

Despite its flaws, EPWING format is still regarded as a trusted source owing to its traditional use, over the more modern crowd-sourced citations.

Software

• EBStudio - (Windows) Used to create EPWING electronic reference materials.
• freepwing on SRA's FTP server - (Unix-like) Used to create EPWING electronic reference materials, mainly through scripting.
• FreeUWING - FreePWING with JIS X 4081 UTF-8 extension - (Unix-like) same as FreePWING but with UTF-8 extensions.