The paper presents the outcomes of a practical experiment aimed at the identification of the various types of annotations that can be attached to enterprise strategic data models. The work is part of a more extensive experimentation on different enterprise models perspectives developed inside the ”Semantic Enrichment of Models and Architecture & Platforms” task group of the FP6 IST-508-011 NoE INTEROP, whose goal is to evaluate the appropriateness (and the possible incompleteness) of existing semantic enrichment concepts, techniques, services and tools. Besides the need for multiple ontologies, the experiment enlighten a rather new perspective with respect to the literature on semantic annotation, related to the fact that mathematical objects have to be taken into consideration.