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51-526: The shapefile format is a geospatial vector data format for geographic information system (GIS) software . It is developed and regulated by Esri as a mostly open specification for data interoperability among Esri and other GIS software products . The shapefile format can spatially describe vector features: points , lines , and polygons , representing, for example, water wells , rivers , and lakes . Each item usually has attributes that describe it, such as name or temperature . The shapefile format

102-445: A Microsoft Works database file in the dBase file format so that it can be read by Microsoft Excel . A package is available for Emacs to read xbase files. LibreOffice and OpenOffice Calc can read and write all generic dbf files. 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

153-481: A 10-percent raise, and then prints the names and salaries. Note how one does not have to keep mentioning the table name. The assumed ("current") table stays the same until told otherwise. Because of its origins as an interpreted interactive language, dBase used a variety of contextual techniques to reduce the amount of typing needed. This facilitated incremental, interactive development but also made larger-scale modular programming difficult. A tenet of modular programming

204-411: A magazine devoted to the professional use of dBase, Data Based Advisor ; its circulation exceeded 35,000 after eight months. All of these activities fueled the rapid rise of dBase as the leading product of its type. As platforms and operating systems proliferated in the early 1980s, the company found it difficult to port the assembly language -based dBase to target systems. This led to a rewrite of

255-876: 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 treated 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 such as VP-Info 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. BYTE ' s Jerry Pournelle in July 1980 called Vulcan "infuriatingly excellent" because

306-515: A new member of the xBase family was born: the XSharp (X#) language, maintained as an open source project with a compiler, its own IDE, and Microsoft Visual Studio integration. XSharp produces .NET assemblies and uses the familiar xBase language. The XSharp product was originally created by a group of four enthusiasts who have worked for the Vulcan.NET project in the past. The compiler is created on top of

357-413: A planned dBase Advisor Magazine was aborted due to the market failure of dBase IV. By the year 2000, the xBase market had faded as developers shifted to new database systems and programming languages. Computer Associates (later known as CA) eventually dropped Clipper. Borland restructured and sold dBase. Of the major acquirers, Microsoft stuck with xBase the longest, evolving FoxPro into Visual FoxPro, but

408-487: A port of dBase for the then-in-development PC. The resultant program was one of the initial pieces of software available when the IBM PC went on sale in the fall of 1981. dBase was one of a few "professional" programs on the platform then, and became a huge success. The customer base included not only end-users, but an increasing number of "value added resellers", or VARs, who purchased dBase, wrote applications with it, and sold

459-575: A programmer at JPL, to write an enhanced version of RETRIEVE, which became the JPLDIS project. JPLDIS was written in FORTRAN on the UNIVAC 1108 mainframe, and was presented publicly in 1973. When Hatfield left JPL in 1974, Jeb Long took over his role. While working at JPL as a contractor, C. Wayne Ratliff entered the office football pool . He had no interest in the game as such, but felt he could win

510-448: A table statement which made referencing a table field unambiguous and simple. For example. one can open a table and assign an alias to it in this fashion, "use EMP alias Employee", and henceforth, refer to table variables as "Employee->Name". Another notable feature is the re-use of the same clauses for different commands. For example, the FOR clause limits the scope of a given command. (It

561-405: Is a digital vector storage format for storing geographic location and associated attribute information. This format lacks the capacity to store topological information. The shapefile format was introduced with ArcView GIS version 2 in the early 1990s. It is now possible to read and write geographical datasets using the shapefile format with a wide variety of software. The shapefile format stores

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612-465: Is an example of a feature that made dBase programming flexible and dynamic, sometimes called "meta ability" in the profession. This could allow programming expressions to be placed inside tables, somewhat reminiscent of formulas in spreadsheet software. However, it could also be problematic for pre-compiling and for making programming code secure from hacking. But, dBase tended to be used for custom internal applications for small and medium companies where

663-455: Is not documented by Esri. However it has been reverse-engineered and documented by the open source community. The 100-byte header is similar to the one in .shp . It is not currently implemented by other vendors. The .sbn file is not strictly necessary, since the .shp file contains all of the information necessary to successfully parse the spatial data. The shapefile format has a number of limitations. The shapefile format does not have

714-556: Is prefixed with a record header of 8 bytes: Following the record header is the actual record: The variable-length record contents depend on the shape type, which must be either the shape type given in the file header or Null. The following are the possible shape types: Optional : M Optional : M range, M array Optional : M range, M array Optional : M range, M array Optional : M range, M array Optional : M range, M array Optional Fields : M range, M array Optional : M range, M array The index contains positional index of

765-404: Is public knowledge, and has been implemented in many dBase clones known as xBase . The open-source shapefile C library, for example, calls its format "xBase" even though it's plain dBase IV. The names and values of attributes are not standardized, and will be different depending on the source of the shapefile. This is a binary spatial index file, which is used only by Esri software. The format

816-451: Is somewhat comparable to SQL's WHERE clause.) Different commands such as LIST, DELETE, REPLACE, BROWSE, etc. could all accept a FOR clause to limit (filter) the scope of their activity. This simplifies the learning of the language. dBase was also one of the first business-oriented languages to implement string evaluation . Here the "&" tells the interpreter to evaluate the string stored in "myMacro" as if it were programming code. This

867-454: Is that the correct execution of a program module must not be affected by external factors such as the state of memory variables or tables being manipulated in other program modules. Because dBase was not designed with this in mind, developers had to be careful about porting (borrowing) programming code that assumed a certain context and it would make writing larger-scale modular code difficult. Work-area-specific references were still possible using

918-477: The .dbf component file is based on an older dBase standard. This database format inherently has a number of limitations: Because the shape type precedes each geometry record, a shapefile is technically capable of storing a mixture of different shape types. However, the specification states, "All the non-Null shapes in a shapefile are required to be of the same shape type." Therefore, this ability to mix shape types must be limited to interspersing null shapes with

969-562: The .shp file, but alone is incomplete for distribution as the other supporting files are required. In line with the ESRI Shapefile Technical Description , legacy GIS software may expect that the filename prefix be limited to eight characters to conform to the DOS 8.3 filename convention, though modern software applications accept files with longer names. In each of the .shp , .shx , and .dbf files,

1020-511: The AutoCAD shape font source format, which shares the .shp extension. The 2D axis ordering of coordinate data assumes a Cartesian coordinate system , using the order (X Y) or (Easting Northing). This axis order is consistent for Geographic coordinate systems , where the order is similarly (longitude latitude). Geometries may also support 3- or 4- dimensional Z and M coordinates, for elevation and measure, respectively. A Z-dimension stores

1071-521: The CP/M port caught the attention of Ashton-Tate in 1980. They licensed it, re-released it as dBASE II , and later ported it to IBM PC computers running DOS . On the PC platform in particular, dBase became one of the best-selling software titles for a number of years. A major upgrade was released as dBase III and ported to a wider variety of platforms, including UNIX and VMS . By the mid-1980s, Ashton-Tate

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1122-572: The Roslyn compiler code, the code behind the C# and VB compilers from Microsoft. Today, implementations of the dBase language have expanded to include many features targeted for business applications, including object-oriented programming, manipulation of remote and distributed data via SQL, Internet functionality, and interaction with modern devices. The following example opens an employee table ("empl"), gives every manager who supervises 1 or more employees

1173-550: The Soviet Union . Its adaptation to the Russian language was reduced to the mechanical replacement of the name, the russification of the help files and the correction of the sorting tables for the Russian language. Introduced in 1988, after delays, dBase IV had "more than 300 new or improved features". By then, FoxPro had made inroads, and even dBase IV's support for Query by Example and SQL were not enough. Along

1224-489: The ANSI/ISO standard language for creating, modifying, and retrieving data stored in relational database management systems. Eventually, it became clear that the dBase world had expanded far beyond Ashton-Tate. A "third-party" community formed, consisting of Fox Software, Nantucket, Alpha Software, Data Based Advisor Magazine, SBT and other application development firms, and major developer groups. Paperback Software launched

1275-524: The Fox products). In December 1990, U.S. District judge Terry Hatter Jr. dismissed Ashton-Tate's lawsuit and invalidated Ashton-Tate's copyrights for not disclosing that dBase had been based, in part, on the public domain JPLDIS . In October 1991, while the case was still under appeal, Borland International acquired Ashton-Tate, and as one of the merger's provisions the U.S. Justice Department required Borland to end

1326-437: The ability to store topological relationships between shapes. The ESRI ArcInfo coverages and many geodatabases do have the ability to store feature topology. The size of both .shp and .dbf component files cannot exceed 2 GB (or 2 bytes) — around 70 million point features at best. The maximum number of feature for other geometry types varies depending on the number of vertices used. The attribute database format for

1377-413: The arrow notation ("B->customer") so that multiple tables could be manipulated at the same time. In addition, if the developer had the foresight to name their tables appropriately, they could clearly refer to a large number of tables open at the same time by notation such as ("employee->salary") and ("vacation->start_date"). Alternatively, the alias command could be appended to the initial opening of

1428-755: The completed systems to their customers. The May 1983 release of dBase II RunTime further entrenched dBase in the VAR market by allowing the VARs to deploy their products using the lower-cost RunTime system. Although some critics stated that dBase was difficult to learn, its success created many opportunities for third parties. By 1984, more than 1,000 companies offered dBase-related application development, libraries of code to add functionality, applications using dBase II Runtime, consulting, training, and how-to books. A company in San Diego (today known as Advisor Media) premiered

1479-419: The correct position in the .shp file. It is also possible to seek forwards an arbitrary number of records using the same method. It is possible to generate the complete index file given a lone .shp file. However, since a shapefile is supposed to always contain an index, doing so counts as repairing a corrupt file. This file stores the attributes for each shape; it uses the dBase IV format. The format

1530-624: The criteria defined by Dr. Edgar F. Codd 's relational model . It used a runtime interpreter architecture, which allowed the user to execute commands by typing them in a command line "dot prompt". Similarly, program scripts (text files with PRG extensions) ran in the interpreter (with the DO command). Over time, Ashton-Tate's competitors introduced so-called clone products and compilers that had more robust programming features such as user-defined functions (UDFs), arrays for complex data handling. Ashton-Tate and its competitors also began to incorporate SQL ,

1581-418: 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. VP-Info is unique in that it can read all variants of the dbf file structure. A second filetype is the .dbt file format for memo fields. While character fields are limited to 254 characters each,

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1632-586: The elevation of each coordinate in 3D space , which can be used for analysis or for visualisation of geometries using 3D computer graphics . The user-defined M dimension can be used for one of many functions, such as storing linear referencing measures or relative time of a feature in 4D space . The main file header is fixed at 100 bytes in length and contains 17 fields; nine 4-byte (32-bit signed integer or int32) integer fields followed by eight 8-byte ( double ) signed floating point fields: The file then contains any number of variable-length records. Each record

1683-409: The feature geometry and the same 100-byte header as the .shp file, followed by any number of 8-byte fixed-length records which consist of the following two fields: Using this index, it is possible to seek backwards in the shapefile by, first, seeking backwards in the shape index (which is possible because it uses fixed-length records), then reading the record offset, and using that offset to seek to

1734-648: The flexible and fast VP-Info with a unique built-in compiler. The community of dBase variants sought to create a dBase language standard, supported by IEEE committee X3J19 and initiative IEEE 1192. They said "xBase" to distinguish it from the Ashton-Tate product. Ashton-Tate saw the rise of xBase as an illegal threat to its proprietary technology. In 1988 they filed suit against Fox Software and Santa Cruz Operation (SCO) for copying dBase's "structure and sequence" in FoxBase+ (SCO marketed XENIX and UNIX versions of

1785-489: The geometry as primitive geometric shapes like points, lines, and polygons. These shapes, together with data attributes that are linked to each shape, create the representation of the geographic data. The term "shapefile" is quite common, but the format consists of a collection of files with a common filename prefix, stored in the same directory . The three mandatory files have filename extensions .shp , .shx , and .dbf . The actual shapefile relates specifically to

1836-442: The geometry data. Geometry of a given feature is stored as a set of vector coordinates. The binary file consists of a single fixed-length header followed by one or more variable-length records . Each of the variable-length records includes a record-header component and a record-contents component. A detailed description of the file format is given in the ESRI Shapefile Technical Description . This format should not be confused with

1887-421: The lack of protection against copying, as compared to compiled software, was often less of an issue. 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

1938-631: The lawsuit against Fox and allow other companies to use the dBase/xBase language without the threat of legal action. By the end of 1992, major software companies raised the stakes by acquiring the leading xBase products. Borland acquired Ashton-Tate's dBase products (and later WordTech's xBase products), Microsoft acquired Fox Software's FoxBASE+ and FoxPro products, and Computer Associates acquired Nantucket's Clipper products. Advisor Media built on its Data Based Advisor magazine by launching FoxPro Advisor and Clipper Advisor (and other) developer magazines and journals, and live conferences for developers. However,

1989-429: The market. This changed with the poor reception of dBase IV , whose design and stability were so lacking that many users switched to other products. In the early 1990s, xBase products constituted the leading database platform for implementing business applications. The size and impact of the xBase market did not go unnoticed, and within one year, the three top xBase firms were acquired by larger software companies: By

2040-416: The nascent company, decided to change the name to the more business-like "dBase". Pawluk devised the use of lower case "d" and all-caps "BASE" to create a distinctive name. Pawluk suggested calling the new product version two ("II") to suggest it was less buggy than an initial release. dBase II was the result and became a standard CP/M application along with WordStar and SuperCalc. In 1981, IBM commissioned

2091-546: The opening decade of the 21st century, most of the original xBase products had faded from prominence and many had disappeared entirely. Products known as dBase still exist, owned by dBase LLC. In the late 1960s, Fred Thompson at the Jet Propulsion Laboratory (JPL) was using a Tymshare product named RETRIEVE to manage a database of electronic calculators, which were at that time very expensive products. In 1971, Thompson collaborated with Jack Hatfield,

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2142-406: The platform in the C programming language , using automated code conversion tools. The resulting code worked, but was essentially undocumented and inhuman in syntax , a problem that would prove to be serious in the future. In May 1984, the rewritten dBase III was released. Although reviewers widely panned its lowered performance, the product was otherwise well reviewed. After a few rapid upgrades,

2193-487: The pool by processing the post-game statistics found in newspapers. In order to do this, he turned his attention to a database system and, by chance, came across the documentation for JPLDIS. He used this as the basis for a port to PTDOS on his kit-built IMSAI 8080 microcomputer, and called the resulting system Vulcan (after the home planet of Mr. Spock on Star Trek ). George Tate and Hal Lashlee had built two successful start-up companies: Discount Software, which

2244-451: The product is no longer offered. In 2006 Advisor Media stopped its last-surviving xBase magazine, FoxPro Advisor. The era of xBase dominance has ended, but there are still xBase products. The dBase product line is now owned by dBase LLC which currently sells dBASE PLUS 12.3 and a DOS-based dBASE CLASSIC (dbDOS to run it on 64-bit Windows). Some open source implementations are available, such as Harbour , xHarbour , and Clip. In 2015,

2295-419: The shapes in each file correspond to each other in sequence (i.e., the first record in the .shp file corresponds to the first record in the .shx and .dbf files, etc.). The .shp and .shx files have various fields with different endianness , so an implementer of the file formats must be very careful to respect the endianness of each field and treat it properly. The main file ( .shp ) contains

2346-721: The single shape type declared in the file's header. A shapefile must not contain both polyline and polygon data, for example, the descriptions for a well (point), a river (polyline), and a lake (polygon) would be stored in three separate datasets. GIS file formats Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.133 via cp1102 cp1102, Varnish XID 547973552 Upstream caches: cp1102 int Error: 429, Too Many Requests at Thu, 28 Nov 2024 05:50:22 GMT DBase Originally released as Vulcan for PTDOS in 1978,

2397-407: The software was powerful but the documentation was poor. He praised its speed and sophisticated queries, but said that "we do a lot of pounding at the table and screaming in rage at the documentation". "Is [dBASE IV 1.0] worth the wait? I think so", Malcolm Rubel wrote in the magazine in 1989, describing it as "a quantum leap over dBASE III Plus in functionality, power, and ease of use". He said that

2448-483: The system stabilized and was once again a best-seller throughout the 1980s, and formed the famous "application trio" of PC compatibles (dBase, Lotus 123 , and WordPerfect ). By the fall of 1984, the company had over 500 employees and was taking in US$ 40 million a year in sales (equivalent to $ 117 million in 2023), the vast majority from dBase products. There was also an unauthorized clone of dBase III called Rebus in

2499-434: The way, Borland , which had bought Ashton-Tate , brought out a revised dBase IV in 1992 but with a focus described as "designed for programmers" rather than "for ordinary users". For handling data, dBase provided detailed procedural commands and functions to dBase is an application development language and integrated navigational database management system which Ashton-Tate labeled as " relational " but it did not meet

2550-464: Was one of the "big three" software publishers in the early business-software market, along with Lotus Development and WordPerfect . Starting in the mid-1980s, several companies produced their own variations on the dBase product and especially the dBase programming language. These included FoxBASE+ (later renamed FoxPro), Clipper , and other so-called xBase products. Many of these were technically stronger than dBase, but could not push it aside in

2601-424: Was one of the first to sell PC software programs through the mail to consumers, and Software Distributors, which was one of the first wholesale distributors of PC software in the world. They entered into an agreement with Ratliff to market Vulcan, and formed Ashton-Tate (the name Ashton was chosen purely for marketing reasons) to do so. Ratliff ported Vulcan from PTDOS to CP/M . Hal Pawluk, who handled marketing for

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