Data Interchange Format

Comments Not usually considered a graphics format but often a carrier of graphics data. Big- and little-endian issues are moot because data is stored as 7-bit ASCII. The Lotus DIF (Data Interchange Format) is used for the storage and exchange of numeric data between applications such as spreadsheets. Although DIF is not usually considered a graphics file format, it is vector-based and often carries information used to generate both bitmap and vector images. It is of interest because the data is always stored in ASCII format. DIF was developed by Software Arts and originally appeared along with the VisiCalc spreadsheet program, which was first released in 1979. Because most spreadsheet applications have their own native file format for storing information, it is usually not possible for a single application to support every other format. DIF has become one of the commonly used interchange formats, perhaps because it has been around so long. A spreadsheet is a 2D matrix of storage cells, each of which contains numeric data, text data, and formulas. Stored along with the data item in each cell is a unique identifier, usually the coordinates associated with the cell itself. Spreadsheet files also may contain information relevant only to the originating application, which is normally ignored by an application seeking to extract the data for other uses. Popular software applications that support DIF include Lotus 1-2-3 and Borland's Quattro Pro. Since DIF files contain only 7-bit ASCII characters, they can be edited using a simple text editor. DIF is also independent of any hardware issues. where string is any ASCII string, often the name of the file or other identifying information. The header ends with the following: Following this is the actual spreadsheet cell data and records containing information to be used in modifying this data. This section describes the format of the DIF header and the different types of records. The Record Type field identifies the data following the field to the rendering or manipulating application. The Vector value affects the interpretation of the value data and indicates the spreadsheet column to which the value data is to apply. A value of zero means that the data applies to the entire spreadsheet. The value field must be zero if data in the Vector field is nonzero. The string field is contained in double quotes, with empty double quotes ("") indicating an empty string. Only the first four record types must appear in every header: TABLE, VECTORS, TUPLES, and DATA. where string denotes the units of measurement associated with the values in the columns of the spreadsheet. where BOT and EOD are strings (without quotes) denoting beginning-of-table and end-of-data, respectively. The Clearinghouse apparently no longer exists, but you may be able to find this document in archives and libraries under their authorship. It is our understanding that responsibility for DIF maintenance has devolved to Lotus, though it is not clear whether Lotus owns or has access to the original DIF Clearinghouse documents. Lotus, of course, is now owned by IBM. An interesting account of the DIF format, by Candace Kalish and Malinda Mayer, was published in the November 1981 issue of byte magazine. This page is taken from the Encyclopedia of Graphics File Formats and is licensed by O'Reilly under the Creative Common/Attribution license.