Aims: Classification of  European bog   vegetation (Oxycocco- Sphagnetea class);    iden  -tification of  diagnostic species for   the   class    and   vegetation subgroups (orders and alliances); development of  an  expert     system for   automatic classification of  vegetation plots; and production of distribution maps of the Oxycocco- Sphagnetea class and its alliances.Location: Europe.Methods: A  data   set   of  vegetation- plot   records was   compiled to  include various bog types    over    most    of  the   European continent. An   unsupervised classification (beta- flexible linkage    method, Sørensen distance measure) and  detrended correspondenceanalysis (DCA)    ordination were    applied. Formal definitions of  syntaxa based    on  spe -cies  presence  and  covers,  and  respecting  the  results  of  the  unsupervised  classifica-tion, were developed and included in a classification expert system.Results: The Oxycocco- Sphagnetea class,    its  two   orders (Sphagno- Ericetalia  tetralicisand Sphagnetalia medii)  and   seven    compositionally distinct alliances were    formally de -fined.    In  addition to  the   syntaxa included in  EuroVegChecklist, three    new    alliances were distinguished: Rubo chamaemori- Dicranion elongati (subarctic polygon and   palsa mires);    Erico mackaianae- Sphagnion papillosi (blanket bogs   of  the  northwestern IberianPeninsula); and  Sphagno  baltici- Trichophorion  cespitosi (boreal bog   lawns). The   latter alliance is newly described in this article.Conclusions: This   first   pan-   European formalized classification of  European bog   veg -etation partially followed the   system presented in  EuroVegChecklist, but   suggested three  additional  alliances.  One  covers  palsa  and  polygon  mires,  one  covers  Iberian  bogs    with    endemics and   one   fills   the   syntaxonomical gap   for   lawn    microhabitats in boreal    bogs.    A  classification expert     system has   been   developed, which    allows    assign   -ment of vegetation plots to the types described.