An usual card would have a full description of the crystal structure, and then provide you the reflection list. However, some cards don't provide the atomic positions.
The CIF files, instead, provide the description of the crystal structure and the atomic positions. And then using software like VESTA, you can calculate the powder pattern and the reflection list. This is the paper I got the informations about the structure you want:
Article Large interspaced layered potassium niobate nanosheet arrays...
Then, I looked for Kb4Nb6O17 in Crystallography Open Database, and found the structure provided by this CIF attached. I opened this CIF in VESTA, and calculated a powder pattern and reflection list. All this information is equivalent as you possessed the actual card.
If you need more help with this, please let me know.