ASCII files and Text files must have the extension .ascii and .txt, respectively to be automatically identified. Otherwise, they must be read as ``raw ASCII''.
LZW compressed TIFF format files As of Version 2.11, creation of compressed TIFF image files is not supported in imal. LZW- and PackBits-compressed TIFF files are, however, readable. The reason for this discrepancy is the choice by Aldus Corporation of LZW compression, which is patented by Unisys, for the compression algorithm. The most recent TIFF documentation indicates that LZW is now being phased out of TIFF. This means that LZW-compressed TIFF files will soon no longer be a valid image format.