Jumbo Files
Introduced in Qedit 4.3, Jumbo files are files in a new Qedit file format. They are similar in structure to original Qedit files, but Jumbo files can hold lines up to 1,000 characters. In addition, Jumbo files can contain up to 99 million lines.
Starting in Qedit 4.6.57, there is a new workfile format known as Wide-Jumbo. These expanded Jumbo files can hold lines up to 8,172 characters.
If you pass a Jumbo file to a program that knows about Qedit files but not Jumbo files, the file will appear to be empty to the program.