Files such as PDF- and Word-Documents, Excel-Sheets, Powerpoint Presentations contain formatting information beside the readable text. This requires them to be transferred as binary files using CODE_FLAG=BINARY. It assures that XCOM does not check for End-of-line record separators and possible conversion from LF to CRLF or vice-versa which would corrupt the file.
The record length of the binary strings is determined by parameter MAXRECLEN which defaults to 1024.