The term "1998 in the decathlon" does not refer to a widely recognized or established concept in the context of athletics, sports history, or encyclopedic records. There is no specific event, rule change, or milestone in the sport of decathlon universally associated with the year 1998 that is documented in major encyclopedic sources.
The decathlon is a combined track and field event consisting of ten disciplines, and significant developments are typically tied to specific athletes, competitions (such as the Olympic Games or World Championships), or rule modifications by the International Association of Athletics Federations (IAAF), now known as World Athletics.
While decathlon competitions did occur in 1998—including at the 1998 Goodwill Games and various national or regional meets—no singular defining moment or widely recognized thematic significance is associated with the year 1998 in the broader history of the decathlon. Notable decathletes such as Dan O'Brien and Erki Nool were active around that time, but 1998 is not particularly highlighted in their careers compared to Olympic or World Championship years.
Therefore, the phrase "1998 in the decathlon" appears to lack sufficient context or encyclopedic recognition as a distinct subject. It may refer informally to results or standings from that year, but such usage is not standard in authoritative sports references.