The Italian hoagie is defined by the roll and by the dress, not by any one of the meats inside it. Capicola, salami, and ham are shingled with provolone the length of a long Philadelphia hoagie roll, then dressed with shredded lettuce, tomato, raw onion, oregano, hot peppers, and a pour of oil. The defining engineering is the roll: a crust with enough structure to carry a long, layered, oil-slicked load without folding in the middle, and a tender interior that does not fight the filling. The build is the sandwich, and the cured-meat trio is the part that gets argued about least.
The craft is in the layering and the dress working as a system. The meats and cheese are shingled rather than stacked so every bite gets capicola, salami, ham, and provolone together instead of a band of one at a time. The lettuce is shredded, not leafed, so it distributes and adds an even cool crunch through the whole roll. The oil and the oregano are not condiments dropped on top; they season and lubricate the interior so the dry cured meats read as juicy, and the hot peppers and raw onion supply the acid and the sharp top note that cut the fat. The tomato is the moisture risk: applied carelessly it floods the crumb, so it goes in as part of the dressed structure, not a wet afterthought. Built right, a foot of it holds together cold from one end to the other, which is the entire reason the format exists.
The variations are mostly nominal and geographic, the same long-roll idea wearing other cities' names. The New York hero, the New England grinder, and the Westchester wedge are the Italian build under different local words. The hot cousins, the meatball and the chicken parm, treat the same roll as a vessel for a saucy filling and lean on a sturdier crust. Tuna, turkey, and vegetable versions keep the architecture and change the filling. Each of those is a codified build with its own rules, and each deserves its own article rather than being crowded in here.