Correlation sets on invoke activities, which deal with outbound operations, are used to validate that outgoing messages contain data which is consistent with the data contained within specified correlation set instances. The Correlations tab of the Invoke Property Editor allows you to examine or specify a correlation set.
The Correlation properties are:
Correlation Set: Specifies the correlation sets.
Initiate: Specifies the initiation of a correlator.
Pattern: Specifies the pattern associated with the correlation.
For more information see Understanding Correlation. Using the Correlation Wizard.