File Formats
A major legacy of dBase is its .dbf file format, which has been adopted in a number of other applications. For example, the shapefile format developed by ESRI for spatial data in its PC ArcInfo geographic information system, uses .dbf files to store feature attribute data.
Microsoft recommends saving a Microsoft Works database file in the dBase file format so that it can be read by Microsoft Excel.
dBase's database system was one of the first to provide a header section for describing the structure of the data in the file. This meant that the program no longer required advance knowledge of the data structure, but rather could ask the data file how it was structured. There are several variations on the .dbf file structure, and not all dBase-related products and .dbf file structures are compatible.
A second filetype is the .dbt file format for memo fields. While character fields are limited to 254 characters each, a memo field is a 10-byte pointer into a .dbt file which can include a much larger text field. dBase was very limited in its ability to process memo fields, but some other xBase languages such as Clipper treat memo fields as strings just like character fields for all purposes except permanent storage.
dBase uses .ndx files for single indexes, and .mdx (multiple-index) files for holding between 1 and 48 indexes. Some xBase languages include compatibility with .ndx files while others use different file formats such as .ntx used by Clipper and .idx/.cdx used by FoxPro or FlagShip. Later iterations of Clipper included drivers for .ndx, .mdx, .idx and .cdx indexes.
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