The implementation of a domain agnostic software system (such as an enterprise resource planning system or a trading information system) based on the REA model requires a generic, yet highly adaptable software architecture. Building on top of well established academic findings and proposals regarding the REA model we are proposing a software model building on two main concepts: fragments and declarations. Together they establish a single, exible, extendible class hierarchy implemented purely on a database layer. Fragments and declarations are implemented as associative arrays that are enriched with metadata, providing clear access to attributes and their meta information. The system's exibility is drastically increased by enabling the multi-typification of REA entities.