Time scheduling as seen in timetabling processes with few and/or competing resources has exposed complex interoperable time scheduling. Attempts to resolving these time scheduling processes has been undertaken, using several classical methods, with difficulty due to inherent complexities, constraints and conflicting issues. The use of ontology-based approaches to resolve time complexity is recently adopted due to its ease in interoperability and reuse of data. The probability weighted ontology provides the various types of complexity as a requirement for the complexity reduction. To determine the optimality of the resulting timetable required the evaluation of its criteria using the analytical hierarchy process. The need for a formal representation to explicate the intelligent behaviour of the ontology-based framework of the temporal scheduler arises. Hence, this work is aimed at providing that formal representation of the logical part of the ontology. The basic rules handling the constraints in the timetabling process are outlined with the corresponding formal representations of the interval-based logic using first-order logic. The semantic model of the temporal scheduler is further described following Guarino's formal ontology model. The unified modeling language (UML) design of a system framework prototype that adopts the formal model is also given. Through the formal ontology-based framework, all constraints that will give optimality are explicated and incorporated into the allocation reasoned, which results in an optimal formal ontology-based model. This will ensure reliability, ease of use and the likelihood of re-usability of the resulting timetable.