Oh sorry, classic case of not realizing not everyone hears your thoughts :-) For "a", there's a list where "a" is the first letter, and a list where "a" is the

Oh sorry, classic case of not realizing not everyone hears your thoughts :-) For "a", there's a list where "a" is the first letter, and a list where "a" is the second. What I wrote out above is an attempt to show the structure. The letters on the left are possible prefixes for "a", the letters on the right are possible suffixes. Then I stuck "-a-" itself in the middle because that seems like a good visualization.