Polyglot files are usually named with a .bin extension.
The files contain one or more entries with each entry having the following information:
struct entry_t { uint64_t key; uint16_t move; uint16_t weight; uint32_t learn; };
NOTE: All integers are stored highest byte first (regardless of size).
Sometimes the file format is shown as:
struct entry_t { uint64_t key; uint16_t move; uint16_t count; uint16_t n; uint16_t sum; };