The AMLP rules from eg. European directives and FATF guidelines use such forms without further specification "transaction showing unusual patterns", "without clear economic purpose", and often as well all of the transactions of at least $1000 each (but technically as well few transactions for $1000 in total over a short period of time count). The rules are not 100% clear but considering the guidelines spirit it simply requires companies to be suspicious towards their customers, especially if they use VPN services.