The MacroLanguage Brief used was Lisp. This was considered very "avant-guarde" at the time.
Borland bought Brief, sold it for a few years, then stopped altogether. Lately, they bought another powerful TextEditor, CodeWright.
Original BRIEF is a pretty old programme, which could have its copyright expired. I spent hours trying to find the original version, without good results (Google gives me completely unrelated results, because of its name). I'm trying to get it, to get it to work with some leaked old assembly compilers (with expired copyright too), for Motorola 68k and Sh2 processors (A package called SNASM2). Is there any way this BRIEF version can be gotten?
--Trox
It should be noted that Brief was inspired by the capabilities of the Unix emacs editor (but was not a clone). There was a Unix clone of it for a while on the late 80's called Grief, with source on comp.sources, which I believe mutated into the Crisp editor mentioned above.
In the early 90's, Brief brought out a version that added a C-like macro language to the existing Lisp-like one. A BBS participant named Doug MacLean? maintained a comprehensive set of Brief macros to make it emulate the vi editor, and offered them in both macro languages. They are probably still available in an archive somewhere.
A similar product was Mince (Mince Is Not Complete Emacs) from Mark of the Unicorn. Mince evolved into the Final Word word processor, which was subsequently bought by Borland, and offered as the Sprint product.