It seems like you're asking about "A.C. Fundamentals" and specifically mentioning "Lattice-section." However, the term "Lattice-section" doesn't provide enough context for me to fully understand what you're referring to. "A.C. Fundamentals" typically refers to the basic principles and concepts related to alternating current (A.C.) in electrical engineering. This might include topics like voltage, current, impedance, power factor, and basic circuit analysis for alternating current circuits.
If "Lattice-section" is a specific term or concept within the context of A.C. Fundamentals, I would need more information to provide a detailed explanation. If you could provide more context or details about what you're looking for, I'd be happy to help you further.