File Extension Z File Format Compressed ASCII archive (COMPRESS) Z stands for Compressed ASCII archive (COMPRESS). 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 Data deduplication and compression String compression on iSeries using zLib What is the range an image can be compressed?