An alias is a user-specific identifier. Aliases are used to identify all devices owned by the same user (an iPhone, an iPad etc.).
In addition, aliases are used to create segments of application users, based on user-specific properites properties (as opposed to application-specific properties).
Note the difference between aliases and tags: Aliases are user-specific, and each user can only have one alias (shared by all the user's devices).
Tags are app-specific and you can assign multiple tags to the same device
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cleanAliasCache
Removes the device alias from the device's local cache.
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