Applications software is increasingly being seen as a useful addendum to a large company’s portfolio of products and services, and Dun & Bradstreet’s Thomas Cook Travel USA has picked up and will market Air Planner Plus, a program developed by Airplan Systems Inc designed to enable corporate travel managers to find the most desirable air fares according to company travel policies; and chemicals and fibres maker Celanese Corp has formed Corporate Class Software as a subsidiary to develop and market applications, starting with Fastar, a $25,000-for-25-users Personal Computer program that it developed in-house for financial analysis and reporting.