The caches are located on posting boxes in a few of PE's suburbs. Most are easy roadside caches, but caution must be exercised due to the fact that they are located alongside roads that are frequently busy, with high muggle presence. Each cache container contains a letter of the alphabet; complete the series in sequence and note the letter, to enable you to locate the final mystery cache.
No space for trade, BYOP, replace carefully where found.
If you are only looking for Postboxes #10, then the next part won't affect your search and can be ignored. However, if you are looking for something else, perhaps something Germanic, then you are in the right place, and this might help..... 
Carry on, what data would you use now?