Elaies (Ελιές) means olives, and the honest framing on this catalog is that this is a component, not a sandwich: olives as a sometimes-added element in Greek pitas and sandwiches rather than a build of their own. It earns a short page because when olives do go in, they are not neutral filler. They are a concentrated hit of salt, fat, and bitterness that can either sharpen a pita or wreck it, and the difference is entirely in handling.
The role is small but decisive. In a pita or a sandwich, olives are usually added sliced, halved, or as a coarse paste so the flavor distributes instead of arriving as one overwhelming whole olive. Good practice starts with the olive itself: a firm, well-cured Greek table olive, pitted reliably, and used in restraint so it seasons rather than dominates. Against fresh tomato, raw onion, and a fatty grilled meat, a few good olives add depth and a savory edge that salt alone cannot. The failures are predictable. Unpitted olives in a wrapped pita are a genuine hazard and an instant tell of a careless kitchen. Over-salty or harshly cured olives bury everything else and throw the whole balance off. Too many, and the pita stops tasting of its meat and sauce and just tastes briny. Olives also carry a lot of oil, so a build already heavy with tzatziki and grilled fat needs them used sparingly or it tips greasy.
How it shifts depends on the surrounding build and the regional habit. Some assemblies use whole or halved olives for texture; others fold in a chopped olive paste so the flavor is even and the pit risk is gone. In rusk and salad preparations olives play a larger, more structural part, but those, like the Cretan dakos, are their own dishes and deserve their own articles rather than being crowded in here. As a pita and sandwich component, the standard is simple: well-cured, reliably pitted, and used in the amount that seasons the whole rather than the amount that takes it over.