The base combat rules cover hex-scale infantry contact. Advanced Combat is the bucket for everything past that; vehicle engagements where the grid is at a different scale, mech-scale grapples where the controlling-Mass math runs into orbital mechanics, multi-zone fights where two squads operate in parallel encounters with a shared clock.
Page status; stub. This page collects rule extensions as they're added. Until then, the base Combat pillar covers the standard infantry-scale engagement, and the GM is encouraged to scale-up by analogy.