We have found one software suitable in our database for this conversion.
Older charts saved in MS Excel's .xlc format can be still imported even in current version of the program. Once done and imported to one of the lists on the sheet, you can save it as Excel spreadsheet (.xls).
Such xlc to xls conversion can be most likely possible with other spreadsheet programs that support import of .xlc objects, unfortunately there might be not many of them left nowadays.
XLC
An xlc file extension is related to the Microsoft Excel, a spreadsheet editor. An xlc file contains chart.
XLS
Files with xls extension are best known as spreadsheets from Microsoft Excel. A spreadsheet is basically a grid of cells sorted in rows and columns. Each cell can contain text, numeric or formula data. Excel XLS spreadsheets can be opened in most other similar programs, such as OpenOffice.org Calc.