Establishing content traceability between various software artifacts or configuration elements at granular level and identifying the gaps in traceability at each phase is a key challenge in software development. In other disciplines such as manufacturing and systems engineering we can find models, well established principles and practices for formulating and tracing the product parts and composition. This paper extends the system model and product breakdown structure concepts from these disciplines to software systems. We propose a model that provides a granular view of software product composition and content traceability through structured relationships among various software configuration elements. Here, we define the key configuration elements essential for the alignment and traceability, create a structure through interconnected relationships of these elements at each phase and analyze the inconsistencies in the relationship. The model provides a visual representation to understand the completeness at each of the development stages. The content traceability is established from both completeness and correctness perspectives and gaps are identified at each phase. The paper briefly describes the model and initial results from pilot implementation in an industry application.