Type: The connection type can be Total, Partial or Weak.
A total connection means that every occurrence of the entity type participates in at least one occurrence of the relationship type. A total connection is shown by a solid line.
A partial connection (shown by a dashed line) means that every occurrence of the entity type can participate in an occurrence of the relationship type but does not have to participate in any of them.
It is possible to make a Connection "Weak" if the Connection starts at a Relationship and ends at a Weak Entity. The Weak Connection is shown by an arrow from the Relationship to the Weak Entity.
Cardinality
The cardinality is the number of times that an Entity can appear in a Relationship. Between Entities and Relationships there can be a
one-to-one correspondence. To enter a cardinality of '1', click next to 1. This value is not displayed in the diagram unless you click in the visible box.
fixed cardinality, shown by a number. To enter a fixed cardinality, click next to n, click on the line n=, type a number then click on OK.
variable cardinality, shown by a letter. Typically, the letters 'n' and 'm' are used. To enter a fixed cardinality, click next to n (or m) and then click on OK. Alternatively, you can click next to n (m), click on the line n= (m=) and type a letter of your choice.
range of cardinality, shown by two values within brackets, representing upper and lower bounds.
To enter a range with a lower bound of 1 and a variable upper bound, click next to (1,n) then click on OK.
To enter a range with variable lower and upper bounds, click next to (n,m) then click on OK. To enter a range with fixed values, click next to (n,m), click on the line n= and type a number, click on the line m= and type a number, then click next to OK.
Rolename
The rolename identifies the specific function that the Entity performs in the Relationship. To enter a rolename, click on the line Rolename, type the Rolename and then click on OK.