Table 2.

Triple-structure of the subject, predicate, and object in the concept layer

	subject	predicate	object
1	Entity (Basic information)	select	Attributes (Name, Sex, etc.)
2	Entity (Report)	has_a	Entity (Basic information, Mammography information, BI-RADS information)
3	Entity (Mammography information)	instance_of	First-level entity (Common signs, Merge signs, etc.)
4	First-level entity (Common signs, Merge signs, etc.)	part_of	Second-level entity (Mass, Calcification, Structure, etc.)
5	Second-level entity (Structure, Mass, etc.)	select	Attributes (Location, Size, etc.)