How do I parse the syntax of the route instruction on a German railway ticket?

Question

With a Deutsche Bahn Flexpreis ticket, one can take any trains on the day of travel, but the route is still limited. The permitted route along which the ticket is valid is written on the ticket, but in a rather cryptic way. For example:

VIA: (MD/BOK*SDL*H)*GOE*(FD/KS*GI)*HU

Or:

VIA: VAI*(PF*KA*SIF*MZ/BR*HD*MA)*F

I have found a list of abbreviations: MD is Magdeburg, BOK is Berlin Ostkreuz, SDL is Stendal, H Hannover, GOE Göttingen, FD Fulda, KS Kassel, GI Gießen, HU Hanau, VAI Vaihingen, PF Pforzheim, KA Karlsruhe, SIF Schifferstadt, MZ Mainz, BR Bruchsal, HD Heidelberg, MA Mannheim, and F Frankfurt.

But what is the meaning of the syntax with parentheses, solidus, and asterisks? I suppose they may have meanings related to either/or, and, may, must, but I cannot find a full explanation anywhere, only explanations of specific cases. How do I read those route instructions?

Answer 1

The solidus designates a bounded area ("Raumbegrenzung"). Any route that passes through the designated stations or between them is covered by the ticket.

The asterisk means that the route must pass through the named station. I suspect, but have found no online confirmation of this, that the asterisk has priority over the solidus, because assuming the converse seems to lead to an absurd result. If this is correct, then the ticket is valid for any route that:

1. passes through
   1. Magdeburg, or
   2. Berlin Ostkreuz, Stendal, and Hannover, or
   3. the region bounded by the two aforementioned routes, and
2. passes through Gottingen, and
3. passes through
   1. Fulda, or
   2. Kassel and Gießen, or
   3. the region bounded by the two aforementioned routes, and
4. passes through Hanau.

The link above is to a page on bahnreise-wiki.de which includes the following text describing the route description SIN*(OG/S) on a ticket to Karlsruhe:

Die beiden anderen Orte sind eingeklammert und mit einem Schrägstrich getrennt. Die so getrennten Orte beschreiben eine sog. Raumbegrenzung, d.h. die Fahrkarte ist sowohl gültig auf der Strecke über Offenburg als auch über Stuttgart und darüber hinaus auf den Strecken zwischen diesen beiden Punkten, sofern die Strecken auf das Ziel Karlsruhe hinführen.

Translation (mine; corrections welcome):

The two other places are enclosed in parentheses and separated by a slash. These places describe a so-called "bounded area," meaning that the ticket is valid both on the route through Offenburg and on the route through Stuttgart, as well as on the routes that pass between these two points, inasmuch as these routes lead to Karlsruhe.

There is also a helpful graphic illustrating the concept. The image is licensed under CC BY-SA 3.0, but I'm nonetheless uncertain about reproducing it here.