To cope with growing complexity of embedded software, modeling has become popular. The usage of models in embedded software industry and the relevant practices usually vary since the purposes of diagram development and usage differ. Since a large variety of software modeling practices used in embedded software industry, it is important to understand its state-of-the-practice and its usage degree while investigating the relations between its attributes (e.g., modeling rigor, purpose, code correspondence, stakeholder, medium used while modeling, etc). To achieve this, we have designed and conducted a survey in our earlier work. In this paper, we present a conceptual model of development and usage for software modeling that is based on the findings of this survey and incorporates expert opinions. The conceptual model, which characterizes the attributes of a diagram development and usage, will help to express the meaning of terms used by domain experts to discuss the problems and find the relationships between these attributes.