When constructing a production possibility curve for an economy what is held constant?

When constructing a production possibility curve (PPC) for an economy, several factors are held constant, including the available resources, technology, and the state of production efficiency. The PPC illustrates the maximum possible output combinations of two goods or services that can be produced with the given resources and technology. It assumes that these factors do not change during the analysis, allowing for a clear representation of opportunity costs and trade-offs between the two goods.