The definition of an Enterprise Architecture (EA) has a central role in implementing Information Systems (ISs)
that proactively contribute to business and Information Technology (IT) alignment. In this paper, using a set of key
concepts for the Information System Architecture (ISA) specification (formalized in a UML profile), 16 metrics are
proposed for ISA suitability assessment considering a set of required quality characteristics. This paper also proposes
an exploratory approach for the ISA definition process. This approach combines EA primitives and metrics in order
to support multi-criteria ISA selection. The proposals presented in this research are applied in the definition, evaluation
and comparing of different architectural options for the new Portuguese National identification document
project (the Citizen Card project).