Which of the following is NOT typically required on a smog repair invoice?

The correct choice highlights that a parts inventory is not typically required on a smog repair invoice. A smog repair invoice primarily focuses on documenting the specific services rendered and the repairs made to address emissions-related issues. Important elements of the invoice include causal analysis, which explains the problem diagnosed, correction measures that detail the repairs performed, and complaint details outlining the customer's reported issues.

While a parts inventory could be useful for internal tracking or in certain contexts, it is generally not mandated as a component of a smog repair invoice. The central aim of the invoice is to provide a clear understanding of what was done to address the smog compliance issues rather than itemizing each part utilized in the process. This distinction helps streamline the invoice to focus on compliance and repair outcomes rather than detailed inventory management.