  The design of complex man-made systems mostly involves a conceptual modeling
phase; therefore, it is important to ensure an appropriate analysis method for
these models. A key concept for such analysis is the development of a
diagramming technique (e.g., UML) because diagrams can describe entities and
processes and emphasize important aspects of the systems being described. The
analysis also includes an examination of ontological concepts such as states
and events, which are used as a basis for the modeling process. Studying
fundamental concepts allows us to understand more deeply the relationship
between these concepts and modeling frameworks. In this paper, we critically
analyze the classic definition of a state utilizing the thinging machine (TM)
model. States in state machine diagrams are considered the appropriate basis
for modeling system behavioral aspects. Despite its wide application in
hardware design, the integration of a state machine model into a software
system s modeling requirements increased the difficulty of graphical
representation (e.g., integration between structural and behavioral diagrams).
To understand such a problem, in this paper, we project (create an equivalent
representation of) states in TM machines. As a case study, we re-modeled a
state machine of an assembly line system in a TM. The outcome is a complicated
picture of assembly line behavior. Therefore, as an alternative solution, we
re-modeled the assembly line based solely on the TM. This new model presents a
clear contrast between state-based modeling of assembly line behavior and the
TM approach. The TM modeling seems more systematic than its counterpart, the
state machine, and its notions are well defined. In a TM, states are just
compound events. A model of a more complex system than the one in the assembly
line has strengthened such a conclusion.
