When a file is read or inserted, Xcoral looks for a magic number in an exec header at the beginning of the file. If this magic number is encountered the command fails.
However, it is possible to display binary files or data, but the characters that are not drawable are viewed as a reverse question mark (191). This question mark is displayed only when the Xlib function XTextWidth returns 0 for the character. Unfortunately this is implementation dependent and in some cases, a simple blank character is viewed.
The Ctrl-q command (quoted char) allows you to insert
a non drawable character. For instance to insert a ^L (new page),
just type Ctrl-q Ctrl-l.