The Styrian or Steïrische Harmonika

The steïrische harmonika is a type of diatonic bisonoric accordion, which is still used in the folkloristic music of Austria, the Czech Republic, Slovenia, the German state of Bavaria and the Italian South Tyrol. The adjective "steïrische" comes from the Viennese dialect and refers to the folk music in general. There is no relationship to the nearby state Steiermark or Styria, though in English the instrument is called styrian accordion. The first instruments were built around 1876.

The instrument is distinguished from other diatonic accordions by its typical richer bass notes. These bass tones are called "Helikonbässe". Bigger reeds are used with duraluminium reed frames and a steïrisch harmonika also has a special chamber construction that amplifies the bass tones. In this way the basses give a loud sound, remeniscent of a "Helicon Tuba".
On the melody side there are three to five rows of buttons, where each row has its own key. The most usual keys are G, C, F and Bes. If wanting to play a melody in D, one will need an instrument with the keys A, D, G, C. On compression of the bellows, the buttons of one row play the tones from the key's tonic, on expansion the same buttons play the tones from the key's dominant seventh. In this way, often melodies require playing buttons from different rows because they cannot be decompressed into tones from the tonic and dominant seventh of a given key. The steïrische harmonika also has one note per scale row that sounds the same while compressing or expanding the bellows. This note is called the "Gleichton".
At the bass side: for each row on the melody side, there are two associated keys on the outer row of the bass side, one for the root and one for the harmony. On compression these buttons play the tone, on expansion they play the dominant. The function of the inner row varies by manufacturer.

As for the music notation for a steïrische harmonika, this is also a different story. The notes on the instrument are placed in such a way, that it is easy to play music with tonality characteristics of alpine folk music, but this makes it difficult to play according modern musical notation.

In 1916 the Verlag Helbling Publishers already tried to make this easier by creating a new tablature, which the also patented. Yet this type of music notation is no longer in use. it was replaced by "Griffschrift". This type of notation was invented by Max Rosenzopf, a music teacher from Bärnbach in Styria. His notation looks similar to modern notation, but maps tones differently to positions on the staff. In 1975 Rosenzopf founded the "Verlag Preissler Publishing Company" and printed the first book using the griffschrift to teach reading notes. Nowadays all music for steïrische harmonika is written using this notation.
Griffschrift looks like modern notation, but the notesigns do not represent the musical notes do, re mi, ..., but the place of the button on the instrument. The notesign also shows on which row the button is: a sign between the lines means on row 1, on the lines is on row two, a note between the lines but proceded by x on row three and a sign on the line proceded by * means the button is on row 4. The line under the "notes" tells how to use the bellows. So, looking at a score in griffschrift, it is not completely what we are used to ...

Sources: http://en.wikipedia.org/wiki/Steirische_Harmonika, http://www.hotforum.nl/forum/pohorje/79833/steirische-harmonika        http://de.wikipedia.org/wiki/Steirische_Harmonika#Historische_Bauweise