Chapter 7: 4GL Language Up Chapter 7: 4GL Language Section 7.2: Summary: 

7.1 Introduction

The 4GL programming language was born in Informix Corp in 1986. Because of that, and not to conflict with with 4GL as general programming concept (BASIC is in principle also a Fourth Generation Language, as opposed to C, which is a Third Generation Language), we should refer to basic 4GL syntax as I4GL.
Today, even among Informix-distributed products, there is distinction between classic I4GL and D4GL (Informix name for 4J’s 4GL compiler), which introduced a number of language enhancements. Then Informix implemented some of these enhancements back into classic 4GL, and added some of it’s own (v 7.3), which 4J in turn implemented in its Universal Compiler V3 (this is the actual name for 4Js product that Informix distributes under the name D4GL - Dynamic 4GL.)
We refer to the syntax of different implementations as:
Luckily for us, Querix decided not to change the language, but instead do all GUI related configuration from separate configuration files.
Aubit 4GL, as a package, and A4GL, as a language definition, is a superset of I4GL.
Our first aim is to provide full unconditional compatibility with I4GL. Since this means that 90% of the syntax used in A4GL will be I4GL, and since this document is not intended to be an I4GL manual, we strongly suggest that you refer to existing Informix documentation and tutorials downloadable from their web site, and books about 4GL, like:
Informix Unleashed, (ISBN 0672306506) a complete book in HTML format about Informix products, by John McNally. You will find several complete chapters about 4GL language there, including chapters on Informix database servers. You will also learn there that "To develop with a 4GL, the developer does not have to be an expert programmer".
(I have asked the author for permission to include his book in Aubit 4GL distribution, but received no answer)
The rest of this page will serve as a quick and dirty crash course to give you some idea of what the I4GL looks like, as a language.
For A4GL extensions. please refer to the appropriate sections of this manual.
 Chapter 7: 4GL Language Up Chapter 7: 4GL Language Section 7.2: Summary: