LINC ("Logic and Information Network Compiler") is a fourth-generation programming language, used mostly on Unisys computer systems. Background LINC was originally developed as a short-cut (or template) by two programmers to reproduce and automate the production of computer applications for different companies, that had similar requirements and specifications. The requirements were similar, because the companies followed a common, generic, business model. That is, these businesses dealt with "commodities", or "parts", or "suppliers", or "customers" (named "components" in LINC terminology). These were "manufactured", or "assembled", or "purchased", or "sold" (actions termed "events" in LINC terminology). These components and events were the "interface specifications" or "ispecs" and contained the database definitions, screen designs, and business rules of the application system. LIRC (Logic and Information Report Compiler) was part of LINC and was developed to allow the programmer to produce reports (e.g. "purchase orders", "invoices", "credit notes", "consignment notes", "bills of sale"). The information in these reports were accessed by using various user-defined views of these components and events called "profiles". Because reports run as a separate task (as a separate thread of execution) they could also be written to run as a background process; that is, it could put itself to sleep for a period of time or until woken, to perform some processing, then put itself to sleep again. Part of the reason for the introduction of this new terminology was to make the system easier for programmers. It isolated them from a lot of the underlying technology. (Similarly, different names were intentionally used for control structures: DO.WHEN rather than IF or LOOP, and LOOK.UP or DETERMINE rather than READ, with the OPEN and CLOSE statements generated automatically.) What allowed LINC to make programmers much more efficient and the application systems they produced easier to read and maintain, and differentiated it from being simply yet another third generation high level language, was LINC's assumption, use of, and total reliance on all of the facilities available, and packaged, with the Burroughs computer for which it was written: operating system, job control language, COBOL programming language, database management system, network definition, user terminal, etc. (See also "history" below.) From version 11, its character changed. Where LINC (and LIRC) specifications had previously been held in source-code files, they were now held in a database (designed and developed using the LINC 4GL) and subject to rigorous automatic validation. The new LINC-based system in which specifications