(1) (
AutoCAD 
Development 
System)  See 
ObjectARX.
(2) (
Automatic 
Dependent 
Surveillance)  See 
ADS-B.
(3) (
Alternate 
Data 
Stream)  A Windows NTFS feature that enables one file to be embedded within another.  An ADS can be used to store thumbnails and summaries within a file; however, regular file managers do not detect the embedded file name or increase in size.  As a result, malware can be injected into a file as an ADS and cause harm when activated at a later date.  See 
NTFS.