Various programs can process DOT files. Some, such as "dot", "neato", "twopi", "circo", "fdp", and "sfdp", can read a DOT file and render it in graphical form. Others, such as "gvpr", "gc", "acyclic", "ccomps", "sccmap", and "tred", read DOT files and perform calculations on the represented graph. Finally, others, such as "lefty", "dotty", and "grappa", provide an interactive interface. The "GVedit" tool combines a text editor with noninteractive image viewer. Most programs are part of the Graphviz package or use it internally.