How to read the result
Each side shows the state in the chosen year according to the entries in the input material. “No entry” means that the material is silent, not that the institution did not exist. “Not yet” appears only where the material points to a later addition, and the marker says what is missing. Before 1920 the districts that are now Czech belonged to Cieszyn, so the lack of a separate institution was not then a shortfall.
The Railway station | Nádraží pair does not mean two equivalent buildings. According to the material the station has stood on the Czech side since 1871, while on the Polish side “not yet” refers to a connection of its own to the Polish network (the line of 1934), not to the station itself. Whether a separate station existed on the Polish side, the material does not settle.
The year 1920
The border came into being in July 1920, and the model counts years, not months. For 1920 the page shows both states: before July and from July. Where they differ, the marker says “change in July 1920”.
Sides of the Olza
The sides are named after today’s state, not by direction. V2 described the banks as “left” and “right” and as “west” and “east”; the input material gives no basis for these terms, so they were removed. The geography of the banks has to be checked on a map.
Language
The EN / CS / EN + CS switch changes only the language of the descriptions, markers, legend and result sentence. The dates, states and result stay the same. The large names of the functions always stand as a pair: the English one on the Polish side, the Czech one on the Czech side. The Czech texts are an editorial translation that needs checking.