Terminologies used in OPA

Rule: A rule is an assertion that a conclusion can be drawn from a particular state of affairs.

Eg: If you leave the ice cream in the sun, then the ice cream will melt.

Each rule must have a conclusion (the state of affairs that can be determined) and usually has at least one condition (the conditions upon which that determination may be made). A conclusion is the "Then" part of an "If... Then..." statement. A condition is the "If" part of an "If... Then..." statement.

Eg:

Conclusion: the ice cream will melt

Condition: If you leave the ice cream in the sun

Attribute: An attribute is a single unit of data or fact.

          Eg:    the ice cream will melt

you leave the ice cream in the sun

Connecting conditions: When a rule contains multiple conditions they can be connected using and And or and Or operator. 

            Eg: A or B and C

Grouping Conditions: Conditions can also be grouped with grouping attributes like All or Any

Eg: A is true if

          B or

          All

          C and D

Which means: A is true if B or (C and D)