There are 2 file types use the .XLC file extension:
1. Excel Chart
Chart created with data from a Microsoft Excel spreadsheet; can be generated from a selection of data by selecting Insert→Chart within Excel; may be saved within the Excel spreadsheet (.XLS file) or separately as an XLC file.
NOTE: XLC files are no longer supported by Excel 2007 and later.
Updated: April 9, 2020
2. Microsoft Excel Chart
An XLC file contains a chart created by Microsoft Excel, a spreadsheet application included with Microsoft Office. It stores data selected from a Microsoft Excel spreadsheet that was exported into Excel chart format. Microsoft dropped support for XLC files with the release of Excel 2007.
Before Microsoft ended support for the XLC format, you could generate a chart by selecting data in a Microsoft Excel spreadsheet, then choosingwithin Excel. You could then save the chart within an Excel spreadsheet (.XLS file) or separately as an XLC file.
You can still create charts within Excel by selecting, and then adjust their settings in the "Chart Design" tab. Instead of allowing you to save the charts in a separate XLC file, Excel saves the chart in the spreadsheet.
NOTE: XLC files are now rare since Microsoft Excel no longer supports them.
You can open XLC files with Microsoft Excel 2003 and earlier. All versions of Excel following 2003 do not support XLC files.
Updated: May 18, 2021