What is a 'domain'? II

Last week I referred to a definition of domain that included mention of:

1. A territory over which rule or control is exercised.
2. A sphere of activity, concern, or function; a field: the domain of history. See synonyms at field.
3. Physics. Any of numerous contiguous regions in a ferromagnetic material in which the direction of spontaneous magnetization is uniform and different from that in neighboring regions.
4. Law.
a) The land of one with paramount title and absolute ownership.
b) Public domain.The remaining definitions -

5. Mathematics.
a) The set of all possible values of an independent variable of a function.
b) An open connected set that contains at least one point.
6. Biology. Any of three primary divisions of living systems, consisting of the eukaryotes, bacteria, and archaea, that rank above a kingdom in taxonomic systems that are based on similarities of DNA sequences.
7. Computer Science. A group of networked computers that share a common communications address.
[Source: Answers.com]

- I suggested were connected by language....

There are some very formal definitions of domain from the world of 5. maths. Pulling other words out of the hat isn't the answer, but the idea of mapping between 'domains' is (I think) very important in Hodges' model; even though any mapping is subjective and - in this instance - not evidence based. Is it possible to be presented by an insurmountable edifice - something that terrifies you and yet fascinates at the same time? Well that's maths for me. I'll return to this another time.

Maths, 6. biology and computer science (to follow) are as noted in the first post domains of study. In health care and especially within medicine 'formal languages' has been and remain a major preoccupation in the form of coding and classification schemes. If you follow the links above you'll see they are listed in the SCIENCES page - since they are formal and structured. In order to report on activity locally and epidemiology at a global level, classification and coding is essential.

The links also include examples of languages of nursing. Nurses spend quite some time writing and computers still choke when it come to analysing and reporting on reams of narrative text. Computers still love codes. Although they are becoming ever more versatile, they still crunch numbers or 'data'.

As for computer science 7: in the 1980s I remember seeing graphs depicting 'languages' from microcode and assembler language at the heart of the machine, through to the fuzzy world of written and spoken language. In between there's quite a spectrum covering logic and a huge range of computer programming languages.

Searching the web I suppose I was bound to come across domain specific languages (DSL). There's a couple of videos and Ruby's in the frame. Funny that, I had noticed in Starbucks how some people like to show off their DSL expertise.
One things for sure this really focuses the mind in terms of defining a domain.