Encoded file that has been converted from a binary file to a text file with btoa (Binary to ASCII) encoding; may be used to send a binary file over a protocol that only support text files. Btoa is similar to Uuencode and Base64 encoding, but it creates slightly smaller file sizes. Btoa-encoded files often begin with the text "xbtoa Begin." Btoa files may also have a .B2A file extension.