.OIS File Extension

An OIS file is a theme file created by Origin, a data analysis and graphing application used by various scientists and engineers. It contains settings in XML format that customize the appearance of one or more analyses windows that appear in Origin.

You most likely will never encounter an OIS theme file when using Origin. The file is not meant to be opened by the user. Instead, it stores the settings that are referenced by Origin for analyses.

NOTE: OIS files are typically located in the "AnalysisAndReportTable" folder of the C:\Program Files\OriginLab\Origin <version>\Themes installation.