An .ibs or IBIS file is a representation of a circuit meant to be read by a simulation application such as Cadence Allegro or HyperLynx. IBIS (Input/output Buffer Information Specification) is an EIA (Electronic Industries Alliance) standard. IBIS is a text file in a specific format that represents the current versus voltage and voltage vs. time characteristics of the inputs and outputs of a circuit. IBIS models are the preferred files to provide to customers since the files do not contain any proprietary information about the internal makeup of the components. NDAs are not normally required for IBIS files.