Betweenlayer

Betweenlayer is a term used in technical writing to describe the interface or region that lies between two adjacent layers within a layered system. It is not a formal, universally defined concept with a single canonical meaning, but rather a descriptive label that appears in multiple disciplines to refer to the space, boundary, or mediating components that connect neighboring layers.

In materials science, betweenlayer distance or interlayer spacing refers to the distance between planes in layered materials such as graphite, mica, or transition metal dichalcogenides; this spacing influences mechanical, electronic, and thermal properties.

In software architecture, the betweenlayer is the interface or middleware that mediates between presentation and data layers; it can be implemented as an API gateway, service bus, or other integration layer, enabling decoupling and modularity.

In machine learning and neural networks, the term may describe between-layer representations or features that are computed to facilitate information flow between layers; practice often uses terms like activations, embeddings, or hidden representations rather than "betweenlayer," but the concept is related.

In practical usage, the concept emphasizes boundaries, compatibility, and interfacing standards between layers, and is sometimes used in design discussions to highlight the need for clear contracts and abstraction. Related terms include interlayer, interface layer, middleware, and cross-layer design.