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A small hollow circle where a wire can be connected.
Also known as: Connection point symbol, Test point symbol, Binding post symbol
A small open circle marks a terminal — a point where an external connection is made. It is deliberately drawn hollow so that it cannot be confused with the filled dot marking a permanent junction.
Marks a terminal or connection point where an external conductor may be attached.
Contexts: Technical drawing, Electrical equipment
Is drawn hollow specifically so that it is not read as the filled dot that marks a permanent wire junction.
Contexts: Technical drawing, Electrical equipment
A small hollow circle at the end of a straight line, its interior left open.
Hollow means a terminal; filled means a joint.