U+3309 "㌉" Square Onsu Unicode Character

U+3309 "㌉" Square Onsu is a CJK (Chinese, Japanese, and Korean) compatibility ideograph that represents a square or tate-chū-yoko form of the Japanese word "onsu," which is a unit of weight traditionally equal to approximately 28.3 grams, roughly corresponding to one ounce in the avoirdupois system. This character belongs to the CJK Compatibility block, specifically categorized as a square katakana expression used in East Asian typography to compress the two-kana reading "オン ス" into a single, compact glyph for vertical text writing or narrow formatting needs. While it is less common in modern digital text, it historically appears in specialized contexts such as traditional measurements, older documents, or decorative scripts, serving as a concise representation of a now largely obsolete unit in regions influenced by Japanese measurements.