noun
relation indicator
Computing term for a symbol or marker that indicates a relationship between data elements, such as in databases or formal grammars.
このデータベースでは、関係指示記号として矢印が使われている。
In this database, arrows are used as relation indicators.
Compound of 関係 (relation) + 指示 (indication) + 記号 (symbol). A technical term likely coined in computing contexts.