Visitor stitching guidelines

The following are important guidelines for visitor ID attributes and visitor stitching:

• Uniqueness
  A visitor ID attribute must have at least 3 unique characters and be at least 6 characters long.
  Learn more about visitor ID attribute requirements.
• Case Sensitive
  Visitor ID attribute values are case sensitive so, UserName@example.com is different from username@example.com. If the attribute values contain these variations, use the lower-case enrichment to normalize them.
• Multiple IDs
  Multiple visitor ID attributes are evaluated as an OR condition in order of attribute ID from lowest to highest (oldest to newest).
• Robustness
  Only user identifiers that are guaranteed to match the visitor across devices should be used for visitor ID attributes.
• Stitched Visitor Profile
  When multiple visitor profiles are stitched, the original profiles remain and a new visitor profile is created to store the stitched profiles.
• Avoid Test Data
  Be careful not to capture default or test values in your user identifiers, such as, undefined, unknown, or not set.
• Shared IDs
  Before stitching is enabled, determine how to handle shared IDs, such as those used at libraries or universities, so that multiple visitors are not stitched inadvertently.