U+339A "㎚" Square Nm Unicode Character

U+339A "㎚" Square Nm is a precomposed CJK compatibility ideograph that represents the square of the nanometer, a unit of length equal to one billionth of a meter, with the "n" and "m" characters arranged in a compact, square-shaped block. It belongs to the CJK Compatibility block of Unicode and was included primarily for compatibility with legacy East Asian character encodings, where such combined units were often used in technical and scientific contexts to denote nanomolar concentration or other nanometer-related measurements. While it is functionally equivalent to typing the letters "nm" separately, this single-character form ensures consistent visual alignment and spacing in documents that require precise rendering of unit symbols.