1. A computer-readable storage medium having encoded thereon a file format representative of a workbook within a spreadsheet application, the file format representing the workbook in a modular content framework implemented within a computing apparatus, the computer apparatus being operative to: establish a relationship between a plurality of logically separate modular parts associated with at least the workbook within the spreadsheet application, wherein the relationship is within a relationship hierarchy for the plurality of logically separate modular parts, the hierarchy comprising at least one indication of optional relationships with respect to validation and at least one indication of a one to many relationship, wherein each modular part is associated with a relationship type, wherein at least one of the plurality of logically separate modular parts is a global modular part used without limitation in the file format, wherein at least one of the plurality of logically separate modular parts is a non-global modular part which is shared on a limited basis in the file format, 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; a dialog sheet part containing data associated with workbook dialog; and interrogate each modular part separately without the spreadsheet application and without other modular parts being interrogated to facilitate locating the contents of a worksheet cell within the spreadsheet application, wherein each modular part is one of extracted from and copied from the workbook and reused in a different workbook along with associated modular parts identified by traversing inbound and outbound relationships of the modular part reused.