Some years back I worked with a site that used REFLECTION to download
files from the HP 3000 to PCs at night.  A COBOL program on the HP 3000
dialed out (modem port with modem configured for DTR forced high) to each
site at night.  The PCs were left on at night, sitting in REFLECTION (at
that time it was R1 for DOS), and when the COBOL program saw the numeric
modem result code for a successful connect, it sent a REFLECTION command
to initiate the file transfer.  I seem to remember the command as being:
 
  <esc>&oCreceive c:\dir\file.ext from hostfile
 
The COBOL program had to accept input from the PC (such as the RUN PCLINK
command used to establish the transfer and the result code REFLECTION
sent after the transfer [S|F|U]) but otherwise was fairly simple.  I
would presume that this would still work today.
 
John