A spreadsheet program saves data into a hypertext markup language (HTML) document that can be viewed with a browser program, but persists all of the information associated with that data necessary to maintain formatting and functionality of the data if reintroduced into the spreadsheet program. The HTML document can then be used both for displaying the data over the Internet or other network in a browser program, and also for opening the data in the spreadsheet program. The information necessary for preserving the format and functionality of the data in the spreadsheet program is incorporated into the HTML document using HTML, Cascading Style Sheets (CSS), and Extended Markup Language (XML). HTML is used for expressing cell data information that is displayed in the browser program, CSS are used for expressing cell-level properties of the data, and XML is used for expressing information that is not displayed in the browser program, but which is necessary for some functionality of the data when used in the spreadsheet program. If any formatting of the data are changed to enable display of the data in the browser program as displayed in the spreadsheet program, the original formatting information is retained in a supporting file that is ignored by a browser program.