A lump is any entry in the IWAD directory (also called directory entries or names).
You can save a lump to a file without any control information so another program can process it directly. DeePsea can directly process Graphic, sound and midi lumps without requiring them to be inside of a PWAD. This makes it much more flexible for general composition.
The MAPINFO and SNDINFO lumps, for example, can be saved and the result is a text file you can edit using any text editor.
You can also save a lump to a file with the control information. You can rename the entry to a different name by supplying a different name in the second prompt. This new file can be read in as a PWAD. The new lump name, if any, will replace any existing name or it will be added to the list of names if it is a new name.
The Lump Export dialog lets you export any lump. See Export Dialog Lump
The Lump Import dialog lets you import any lump(s) and create a brand new PWAD (with one or more entries) or extend an existing PWAD. See Import Dialog Lump