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The value provided must be a valid identifier for a Visitor record that exists within the S4S Cloud service for analytics functionality to work.
Identification via URL parameter
The S4S Cloud client also supports setting identification for an existing visitor using the URL parameter s4scid. If this is found and has a non-empty value, S4S Cloud will attempt to use this as the visitor identifier.
https://example.com/subscriptions?s4scid=a123b0000456789ABC
This may be useful for personalized external links, for example via email. If the recipient opens the link in a different browser or on a different device than when first identified, the identification will follow them. This could be used to implement subscription management or other online forms that require a known visitor.