Laboratory Virtual Instrument Engineering Workbench. LabVIEW is a graphical programming language that uses icons instead of lines of text to create programs. structure Program control element, such as a Sequence Structure, Case structure, For Loop, or While Loop. subdiagram Block diagram within the border of a structure. subVI VI used in the block diagram of another VI comparable to a subroutine. VI See virtual instrument(VI). virtual instrument (VI) Program in LabVIEW that models the appearance and function of a physical instrument. waveform chart Indicator that plots data points at a certain rate. While Loop Loop structure that repeats a section of code until a condition is met. It is comparable to a Do loop or a Repeat-Until loop in conventional programming languages. wire Data path between nodes.