DESNAME is an optional 4000 character alphanumeric field that specifies the name of output and depends on the Destination Type.

CACHE Destination name - defaults to Function+Execution ID+Format Suffix
File File name - defaults to Function+Execution ID+Format Suffix
e.g. RDJB#162852.pdf
Email Email recipient - must be entered
Printer Printer name - leave blank - system will provide