AMBOA is a quality label, rather like an appellation contrôlée , guaranteeing the quality of the raw ingredients in chocolate. Specifically, it is a guarantee that the producer does not substitute any fat for cocoa butter.
A disastrous EU directive from 2000 authorises the replacement of up to 5% of the cocoa butter with any other vegetable fat (like shea nuts). The resulting product can still be called chocolate.
Fortunately, those producers that observe the traditions of Belgian chocolate making refuse to exploit this fatuous ruling. But the AMBOA label has not taken off as it would have liked among producers or consumers. There are various reasons, including poor communication and cost.