Many other document formats, such as Microsoft Word .doc and .docx files, or Adobe's Portable Document Format (.pdfs), embed external media directly into their files; you can linearly scan through these documents to find JFIF data. These JPEGs might or might not be accessible in the document; they might live in "slack space" if the document format entails slack. Similarly, you can scan through disk images to extract some JPEGs (though not all, as we'll see later in the semester), and again, files that have been deleted might still be accessible as the data.