The Neliac programming language, a Navy-originated third-generation language
that (with its compiler) was the product of the late computing pioneer Maury Halstead (Halstead later became more famous for his role in defining the software metrics field with his "Software Science") became the basis of our multi-domain language; we used it to code our operating system, our tools and libraries.
"We moved down from a fourth-generation language to a third-generation language
and got a more usable program."
Experienced developers will appreciate the flexibility they gain from advanced language features like associative arrays, regular expressions, support for manipulating binary data, high-level language support for socket communication, and the increased productivity that comes with freedom from the compile/link/debug cycle that is characteristic of development in third-generation languages
like C++, Java, and BASIC.
They are usually discussed in terms of "generations." Cobol and Basic are third-generation languages
. Companies such as Sybase and Informix, among others, produce fourth-generation languages (4GL), and there are a number of lesser-known proprietary 4GL products.