Strategically planning and aligning information systems is still one the most challenging IT tasks for organizations. Literature has contributed to describe and analyze the phenomena labeling the process of Strategic Information Systems Planning (SISP) as the one that pursues the alignment of the IS/IT initiatives to achieve business goals. Statistics reveal, however, that those goals are significantly not being achieved, leaving the discussion open to know whether the SISP models, frameworks and methods are correct, complete, applicable, feasible or not. In order to understand and visualize the potential gaps and biases in the SISP literature, the paper introduces an ontology of the SISP process that allows systematically and symmetrically expand study to contribute to maturation of the scientific field as well as to identify the critical omissions within it. Later, the ontological analysis will allow the visualization of bright, light, and blind/blank areas of knowledge documented on SISP.