The objects listed in this catalogue are subdivided into three main object classes, i.e. into Cataclysmic Binaries, Low-Mass X-Ray Binaries and Related Objects. The defining characteristics of the three object classes used here are the following:
In addition, we list among the cataclysmic binaries also the supersoft binary X-ray sources, because these too are semi-detached binaries containing a white dwarf, though one in a state of sustained nuclear burning. More information about these objects can be found in Greiner (1996).
to 
). A more detailed description of
the main characteristics of these objects may be found in the review
articles in Lewin et al. (1995).
With one possible exception (HD 49798) we do not list among the related objects detached binaries containing a neutron star, or, for the lack of known objects, a black hole. Thus we explicitly exclude binary radio pulsars from our compilation because these are adequately documented elsewhere (e.g. in the Princeton pulsar list (Taylor et al. 1993) and its updates, available via anonymous ftp at pulsar.princeton.edu).
According to the subdivision in these three object classes the catalogue consists of three major parts, hereafter referred to as catalogue sections. Each of the three catalogue sections is further subdivided into a table section, where a few characterizing parameters of the object are tabulated, and into a reference section, where a selection of references is given. Within each of the table sections, the objects are listed in order of decreasing orbital period. In the corresponding reference section, however, the objects are listed in lexigraphical order.
In contrast to the previous editions we provide now limited information about where the values given in the tables are taken from. This is done as follows: at the end of a reference from which a given quantity, say XYZ, was taken, this quantity is given in parenthesis, i.e. as (XYZ). The quantities for which this is done are: the periods (Orb.Per., 2. Per., 3. Per., 4. Per.), the spectral types (Spectr1, Spectr2), the mass ratio (M1/M2), the orbital inclination (Incl), the masses (M1, M2), and, where appropriate, the radii (R1, R2) and the eccentricity (e).
The catalogue is supplemented by a list giving references to published finding charts of the objects. In this separate section, the objects of all three classes are merged and listed in lexigraphical order. The full form of abbreviated references used is given at the end of this section.
Finally, the Who's Who? file contains a cross-reference list of alias names of the objects catalogued. In order to keep this list short, the full list of alternative object names appears only once for each object and is to be found under the standard name used in this catalogue. If an object is sought under one of its alternative names, reference to the standard name is given. Wherever possible the variable name given in the 4th edition of the General Catalogue of Variable Stars (Kholopov et al. 1985a,b, 1987) or in the Name Lists of Variable Stars (up to and including the 73rd list (Kazarovets & Samus (1997), and references therein) is used as the standard name here. This section includes also a list of references to various catalogue acronyms that appear in this compilation. However, references to catalogue acronyms which have already been given in previous editions are not repeated here. A more complete list of this kind may be found in The First Dictionary of the Nomenclature of Celestial Objects by Fernandez et al. (1983), its supplements Lortet (1986a,b), and Lortet & Spite (1986), in the Second Reference Dictionary of the Nomenclature of Celestial Objects by Lortet et al. (1994), or online via the CDS at http://vizier.u-strasbg.fr/cgi-bin/Dic, or from the ADC at http://adc.gsfc.nasa.gov/adc/.
Acknowledgements
We wish to thank H.-C. Thomas for keeping us informed about the latest results regarding the optical identification and follow-up observations of new CVs from the ROSAT All Sky Survey. We thank also A. King for improving the language of the manuscript, and R. Downes, T. Hillwig, E. Kuulkers, T. Naylor, F. Ringwald, C. Tappert and R. Wade, for reporting updates of tabulated values and misprints.