- "custom_button": "Edit custom background",
- "custom_prompt": "Enter a tile URL template. Valid tokens are:\n - {zoom} or {z}, {x}, {y} for Z/X/Y tile scheme\n - {-y} or {ty} for flipped TMS-style Y coordinates\n - {u} for quadtile scheme\n - {switch:a,b,c} for DNS server multiplexing\n\nExample:\n{example}",