P: Letters as file extension

[CS Claudia]

I would really appreciate it if letters instead of numbers were offered for the file extension when exporting. Would help me a lot.

[JohanElzenga]

File extensions are what is written after the dot to specify the file type, such as ".jpg" or ".tiff". I assume you mean that you would like Lightroom to add letters instead of sequence numbers, so something like "originalfilename-A.jpg", "originalfilename-B.jpg"?