A bibliography file consists of a sequence of records, each representing a reference, which is one of several types, including books, journals, conference proceedings, technical reports, project reports, theses, internet resources and even unpublished papers, essays, lecture notes and handouts. REF knows how to generate an entry in a bibliography for any of these types.
Records are enclosed within curly brackets {}, and REF will treat anything outside curly brackets as comments.
Each record should contain all the information needed for the program to generate a bibliography entry for that reference, and REF will warn you of any missing information. REF is trained to look out for specific fieldnames (e.g. Type, Title) when it comes to generating a bibliography.
Each record consists of a set of fields, each of which is in the format "Fieldname = Value" on a separate line, e.g.
Title = Case-Based Reasoning
Some fieldnames have a list of values rather than a single value (in particular Authors, Editors, Cited and Keyword), and you have to learn which is which (the program will tell you if you get it wrong when it attempts to retrieve that record). Lists are enclosed in square brackets [] and have exactly one line for each element in the list, e.g.
Authors = [Brown M.
Filer N.
Moosa Z.]
A field value can even be a nested record, which is enclosed in nested curly brackets. This is used to denote part/whole relationships - in particular, the articles in a journal or the proceedings of a conference. The field "Articles" is a list of nested records. Note that nested records are retrieved just as readily as, and separately from, top-level records. Do not nest records more than two levels deep, unless you modify the program to cope with this!
Study the example bibliography file to learn what fields should be included in references of particular types, what the names of those fields are, and whether their values are single values, lists or nested records. The best way to write a new record is to modify an old one, but beware - mistakes can easily slip in because you forgot to change something!
Note that extra fields can be included in a record that do not affect the generation of the bibliography entry - in particular "Status" (where you can find it), "Cited" (which of your own publications you have referred to it in, if any) and "Keyword" (a list of index terms which describe what the reference is about). I strongly encourage you to tag every reference with its keywords, as this is the most useful feature of REF!
In fact, you can include any extra fields you like in a record, and if REF doesn't recognise the fieldname, it will simply ignore it. So be careful to get the fieldnames right, or REF will baffle you by saying that a field isn't there when it is.
The other caveat is to make sure you respect REF's syntax rules, because the program will not be very sympathetic if you don't! In particular, note REF is very sensitive to newlines, unlike most languages. The basic rule is that the end of a line means the end of a value, so don't try to split a field over multiple lines unless it's a list or a nested record, in which case you have to. The best way to learn the syntax is from the example bibliography file.