To qualify for this cache, you need to have found 26 caches with lone letters in their names, one for each letter of the alphabet. In your log, you must list, for each letter, the name of a cache that you've found, in which that letter occurs by itself, and either a link to your Found log for the cache or the date when you found it. (A link would make my job easier, but it's slightly more work for you, so I won't insist on it.)
It sounds feasible using regex