This term describes a data interface which aims at exchanging data with other programs. When talking about interfaces, it is distinguished between direct formats (via API) and file-based standardized formats.
Input and output data are exchanged in the form of calculation results to use it in other structural engineering software for analysis and design.
Moreover, a software interface is available in RF-COM (for RFEM) and RS-COM (for RSTAB). It is a programmable interface which is based on COM technology to control RFEM and RSTAB.