Which theater deployable communications (TDC) equipment characteristic requires equipment modules to be expandable and packaged for deployment in standard 19-inch rack mounted transit cases?

The characteristic of TDC equipment that emphasizes expandability and packaging for deployment in standard 19-inch rack-mounted transit cases is modularity-scalability. This principle allows the equipment to be easily configured for different operational needs by adding or removing components as necessary.

In a military context, being modular means the equipment can adapt to various communications requirements or environments. Scalability ensures that systems can grow in capability without the need for completely new setups. This is crucial for deploying resources efficiently and ensuring that units can maintain effective communication regardless of the mission scope or changes in requirements.

The other characteristics do not specifically address the need for equipment to be expandable or packaged for deployment in standard cases. Mobility refers to the ease of transporting the equipment, survivability relates to its ability to withstand adverse conditions, and interoperability signifies the ability of systems to work together across different networks and platforms. While these aspects are important, they do not focus on the structure and expandability features inherent in modularity-scalability.