 It contains lists of synonyms arranged into 19 semantic categories (e.g., "Explaining Plants", "Explaining Trees").The Han Dynasty dictionary "Xiao Erya" (小爾雅 "Little Erya") reduces these 19 to 13 chapters.The early 3rd century CE "Guangya" (廣雅 "Expanded Erya"), from the Northern Wei Dynasty, followed the "Erya"s original 19 chapters.