The term "BY 17" primarily refers to a topographic map sheet from the Deutscher Alpenverein (DAV) series, specifically covering the Chiemgauer Alpen West region, including areas like Hochries and Geigelstein in the Bavarian Alps. It is a hiking and outdoor map scaled at 1:25,000, used for activities such as hiking, ski routes, and snowshoe routes with detailed local geographical information. The map is part of a high-quality series jointly developed by the DAV and the Bavarian state office for surveying, updated as recently as 2023-2024.

Additionally, "BY 17" can appear as a model or designation in other unrelated contexts, such as the "X17" notebook system, but the most common and relevant usage seems to be related to the DAV alpine map series.

If the question pertains to a specific context, such as mapping or another domain, please clarify for more detailed information.