| A | B |
|---|
| Historical Data | data that records changes over time |
| Audit Trail | a step by step record of data changes |
| Hierarchial Relationship | a series of relationships that reflect entities organized into successive levels |
| Recursive Relationships | a relationship between a entity an itself |
| Constraint | a restriction that applies to data, which is often dictated by the business rules |
| Exclusive OR Relationship | a logical operator that returns a true value if one, but not both, of its operands are true |
| Mutually Exclusive Relationship | a relationship that has choices that are unable to be true at the same time |
| Arc | a curved line used to represent an exclusive relationship in a ERD |
