An ixs file extension is related to the ArcView and used for its geocoding index for read-write shape data.
Software that open ixs file
IXS file extension - ArcView geocoding index for read-write shape
What is ixs file? How to open ixs files?
File type specification:
The ixs file extension is associated with the ArcView, a GIS software for Microsoft Windows operating system, developed by ESRI.
The ixs file contains geocoding index for read-write shape data.
The default software associated to open ixs file:
ArcGIS for Desktop Basic (ArcView) 
Company or developer:
Esri
ArcGIS for Desktop Basic (formerly known as ArcView) is GIS (geographic information system) application used to visualizing, managing, creating, and analyzing geographic data.
ArcGIS for Desktop Basic is a part of the ArcGIS Desktop. ArcGIS for Desktop Basic supports creation of interactive maps, spatial analysis, GIS deployment, map viewing and navigation, map printing etc.
List of recommended software applications associated to the .ixs file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open ixs file, edit ixs file, convert ixs file, view ixs file, play ixs file etc. (if exist software for corresponding action in File-Extensions.org's database).
Unspecified and all other actions for computer programs working with ixs file - ArcView geocoding index for read-write shape
Click on the software link for more information about ArcGIS for Desktop Basic (ArcView). ArcGIS for Desktop Basic (ArcView) uses ixs file type for its internal purposes and/or also by different way than common edit or open file actions (eg. to install/execute/support an application itself, to store application or user data, configure program etc.).
