An industry-standard format for Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) simulation libraries.

The Quartus^® II software provides VHDL cell simulation models that are compliant with VITAL version 2.2b and version 3.0 (VITAL 95). In addition, the Quartus II Compiler also generates a Standard Delay Format Output File (.sdo) for use with VITAL-compliant simulation libraries.