HOOD (Hierarchical Object Oriented Design) is the standard ESA (European Space Agency) method for the architectural design phase and essentially oriented towards Ada program development. The HOOD method can be described using the so called MASP — Model for Assisted Software Processes — model developed within the ALF project (ESPRIT Ref 1520) that allows the depiction of software development activities for a wide range of methods such that the knowledge encompassed in the method description can be exploited to assist the user leading to the production of more reliable software and a cost reduction. Therefore, a MASP description for the HOOD method could be used as basis for future HOOD toolset developments. Furthermore, representing the HOOD method using the MASP formalism can result in obtaining a greater stage of formalisation and understanding of its semantics. The MASP model has been envisaged as part of a third generation software engineering environment framework based on the interpretation of this software process model and developed within the project ALF [B*89], [GGGS89].