.ATX File Extension
File Type 1ArcGIS Attribute Index File
What is an ATX file?
NOTE: ArcGIS 8 and later use a different attribute index format than ArcView 3.x.
File Type 2Animation Master Plugin File
.ATX File Association 2
Plugin for Animation:Master, an easy-to-use 3D animation program; adds additional functionality, such as graphic and animation effects, to the application.
NOTE: The file "RANDEX.ATX" is a known worm file and should not be opened. Instead it should be deleted or removed with an antivirus program.