The NumberPerf security feature
NumberPerf uniquely identifies documents, as a unique number is perforated. The laser creates holes which have no reverse embossing.
Small slits are laser perforated through the document substrate to form a legible number. Because the perforated alphanumeric information is often unique, the number actually personalises a document.
This has two advantages: firstly, if the same number is also printed on the document close to the perforated number, an easy cross-check is all it takes to authenticate the document.
And secondly, if the number is perforated through another feature such as a hologram, this feature is also personalised and cannot be used to create fake documents.