# Dashed line in Crow's Foot notation

I am learning about the Crow's Foot notation, and there is something that I don't understand, some tutorials shows an Identifying Relationship as having a straight line, and a Non-Identifying Relationship as having a dashed line:

While other tutorials shows both relationships as having a straight line:

Are both notations correct?

• What is this "other tutorials" you speak of? Can you provide one or more links? Nov 4, 2016 at 20:07
• @Robert Harvey This tutorial uses straight lines for Non-Identifying Relationships: college.yukondude.com/2003_09_comp210/html/…, while this tutorial uses dashed lines for Non-Identifying Relationships: codeproject.com/Articles/878359/…
– Tom
Nov 4, 2016 at 20:46
• That Yukondude article refers not to strong and weak relationships, but to strong and weak entities. I assume that he's indicating the Transcript as a weak entity with those little diagonal lines in the corners. But I also assume that's not necessarily standard notation. Nov 4, 2016 at 22:30
• @Robert Harvey What is this notation called (where a Non-Identifying Relationship is represented using a dashed line and an Identifying Relationship is represented using a straight line)? Is it called IE Crow's Foot or Martin Crow's Foot or Martin / IE / Crow's Foot? And does it have an official documentation?
– Tom
Nov 5, 2016 at 13:18

The ends of the relationships have show two values (max and min) indicating the cardinality of the relationship for the table at the other end of the line. The min value has two possible cardinality values zero (`O`) or 1 (`|` or `+` ), The max value also has two possible diagrammed values 1 (`|` or `+`) or many (a crowsfoot). If either min value is zero, then the relationship is optional.