The updated version of ESA's software engineering standard (called PSS
-05) was issued in February 1991. It defines the steps necessary to pr
oduce quality software that meets the user's requirements within the e
stablished timeframe and budget. The standard applies to all software
developed by ESA or its contractors for ground, space, information sys
tems, and operations. It provides a common working culture for the ent
ire European space software community.