interline

Interline is a term used in several fields. In typography and publishing, it most often denotes the vertical distance between lines of text. In transportation, it can describe cross-line train operations. In electronics, it appears in references to interline transfer image sensors.

In typography, interline spacing, or leading, is the vertical distance from one baseline to the next. It is specified in points or as a multiple of font size. Appropriate leading improves readability and controls page balance; it can be tight or loose depending on design. Adjusting interline spacing affects the overall layout.

In railway and transit contexts, interlining refers to the practice of running services that use more than one line or operator, creating through services and junction-style connections. This requires timetable coordination, compatible signaling and rolling stock, and sometimes shared infrastructure or operational agreements. Benefits include longer, more direct itineraries and better network efficiency; challenges include scheduling complexity, capacity conflicts, and interoperability between different systems or national standards.

Interline transfer describes a CCD sensor in which charge moves to a storage register after exposure. This enables faster readout and reduces smear, at the cost of fabrication complexity and usually lower fill factor. Interline transfer sensors are used in some cameras and scientific instruments.