● Covered by 1 source · 1 reportLow impact1 neutral
Investigation reveals origins of JIS X 0208 "ghost characters" in Unicode
Key points
- JIS X 0208, established in 1978, contained characters with unknown origins.
- An investigation in 1997 identified most "ghost characters" as cataloging mistakes.
- One example, 妛, resulted from a copying error of "山 over 女".
- Only one character remains without a clear source or historical precedent.
The Mystery of Ghost Characters
In 1978, Japan's Ministry of Economy, Trade and Industry established the JIS X 0208 encoding, a foundational standard for Japanese character sets. Soon after its release, users noted the presence of several characters with no discernible sources or meanings, leading to their designation as "ghost characters" (幽霊文字). For many years, these characters remained an unexplained curiosity within the standard.
The 1997 Investigation
A formal investigation was launched in 1997 to determine the origins of these mysterious characters. While the JIS standard typically listed sources for its characters, these references were often vague, sometimes only citing large documents like the "Overview of National Administrative Districts," a multi-volume list of Japanese place names, without specific page numbers. This made tracing individual characters exceptionally difficult.
Discovery of Cataloging Errors
Despite the challenges, the investigation successfully identified the origins of most ghost characters. Through interviews with the original catalogers involved in the standard's creation, it was determined that many characters were inadvertently introduced as errors during the cataloging process. For instance, the character 妛 was found to be a mistake that occurred when attempting to record "山 over 女." This error happened during a manual copying process where the line formed by the junction of two separate paper cutouts was mistakenly interpreted as an additional stroke.
Lingering Unexplained Characters
The original character, 𡚴, which "山 over 女" represented, was not included in JIS or Unicode until much later. The investigation concluded that nearly all ghost characters had identifiable origins, primarily stemming from human error during the initial compilation of the JIS X 0208 standard. However, one character ultimately remained without a clear source or any historical precedent, continuing to be a true enigma within the encoding.
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Reporting from
An investigation uncovered the origins of "ghost characters" in the JIS X 0208 encoding, which later influenced Unicode. These characters, whose sources were unknown for decades, were largely found to be cataloging errors during the standard's creation in 1978.