1. A file format for representing a workbook within a spreadsheet application, the file format representing the workbook in a modular content framework implemented within a computing apparatus, the file format comprising: modular parts logically separate but associated by one or more relationships wherein each modular part is associated with a relationship type and wherein the modular parts include: a workbook part operative as a guide for properties of the workbook; and at least one of the following: a worksheet part associated with the workbook part and operative to specify a definition of cells within a worksheet associated with the worksheet part; a sheet part containing data associated with a macro sheet; a chart sheet part containing data associated with defining a chart; and a dialog sheet part containing data associated with workbook dialog; wherein each modular part is capable of being interrogated separately without the spreadsheet application and without other modular parts being interrogated.