Art,
These are all tied to a particular company, hardware, database or product.
They are all so-named to give them appeal to an unsuspecting customer.

In the 'History' section of your first link it states "early 4GLs were included in the Informatics MARK-IV (1967) product and Sperry's MAPPER (1969 internal use, 1979 release)". So I'd conclude that MARK-VI is a product (as stated) and Sperry's MAPPER needs a Sperry Univac to run on.

The article further tries to include "Some advanced 3GLs like Python, Ruby, and Perl combine some 4GL abilities within a general-purpose 3GL environment. Also, libraries with 4GL-like features have been developed as add-ons for most popular 3GLs. This has blurred the distinction of 4GL and 3GL."
So the writer appears to admit that there are now things named "4GL-like features", which just adds to the confusion.

In the progress from (1) Machine Code to (2) Assembler Languages to (3) Compiler Languages, I can write binary code, I can write ASSEMBLER and BASIC, and I can also write FORTRAN, ALGOL, COBOL, PASCAL, PL/1, etc. 

We all know that IMAGE is a database 'language' specific to HP, and I can write a COBOL program to interact with an IMAGE database. Other companies have their similar database products (e.g. Oracle, IBM).

None of the so-called languages in the articles you quote, are taught at university (at least none that I know of), so I'd still proffer that they are 'products' being offered by their specific companies, with a marketing 'spin' that they are the newest gizmo of so-called Fourth Generation Languages.

George Strait has some ocean-front property for sale in Arizona and I know you're just dying to get your feet wet...

Kindest Regards,
Tom.

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