REST (Representational State Transfer) is an interface architecture designed for distributed environments. The REST interface can be used for a simple and unified access to resources. A resource can be data as well as application states (if they can be described using particular data). REST is data-oriented.
In general, REST refers to various types of communication built on HTTP. REST is a simple interface to transfer domain-specific data over HTTP without an added communication layer.
In context of NETIO products
REST refers to protocols built on top of HTTP or HTTPs, including the generic URL API.
Note: PowerCable REST 101x is a separate product of the PowerCable xxx family.