File Extension SPR File Format Document letter (Sprint) SPR stands for Document letter (Sprint). This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question FOI shows bureaucratic bungle behind open standards u-turn How to flash Galaxy S5 How to restore Excel files following format?