writing system
Technical term used in linguistics and language studies to refer to a system of written symbols, such as an alphabet, syllabary, or logography.
The Japanese writing system includes kanji and kana.
文字体系 is a near-synonym also meaning 'writing system', but 書記体系 is slightly more formal and often used in academic contexts.
Compound of 書記 (writing, recording) and 体系 (system). The exact historical derivation is uncertain, but the term is a modern technical coinage.