the line so it doesn't collide with other lines, and in "called" dances to call the variations. New dancers joining a dancing line join at the end; it is bad manners to join at the head of the line, in front of the leader. Regional differences Bulgaria is divided into seven ethnographic regions: Northern Bulgaria, Dobruja, Shopluk, Thrace, Strandzha, Macedonia and Rhodopes. Each region has its own distinctive style of dance, to the extent that a knowledgeable observer can often tell which region a group of Bulgarians comes from by how they perform a popular dance like the pravo. In addition, due to the intricate ethnic mix in the Balkans, each locality and even each village may have its own variation of a dance, different enough that it amounts to a distinct dance. In Bulgarian folkdance literature, local variations are often differentiated by adding the geographical origin to the dance name: for example pravo plovdivsko horo means "the pravo dance from the town of Plovdiv". Rhythm and meter The proportions of the beats do not follow any exact rational proportions. For example, the well-known tune "Eleno Mome" (Елено Моме) exists written in three forms: (1) , (2) , and (3) times. Here, the latter two forms exist both as a musicologist's way to attempt to indicate the tendency of speeding up the last and first beats, as well in formal version, where the musician plays 3 or 4 about equal length notes on the beat. In music band playing, the meter seems favored, thus skipping some of the time-bending subtleties. Given this fact, though, some meters are more common or popular, but there is a wide variation of less frequent combinations, as well. There is also disagreement about whether one should use or as meter denominator, but this is just a notational convenience. In the list below, the denominator follows in part notational practice of the region, and in part the speed of the type of tune, giving the note a reasonable number of beats per minute (as on a metronome). Folk dancers often speak in terms of "quick" and "slow" instead of a steady meter "1, 2, 3," etc. These dance rhythms may not agree with the rhythms and meters performed by the musicians. For example, the rhythm of the dance kopanitsa is often described as quick-quick-slow-quick-quick, () whereas the tune may be played in what may be written