This is an eVLBI control parameter. Be warned: eVLBI support is under development. The eVLBI parameters are GRABTO, GRABTIME, GRABGAP, and DATAPATH.
GRABTO is used to help control sending of small amounts of previously recorded data over the net. That process happens after the scan of interest, which was recorded normally. The data can either be copied first to the system disk, then transfered later by, for example, ftp or some other protocol GRABTO=FILE. Or the data can be sent directly to the net GRABTO=NET from the VLBI disks. It seems that GRABTO=NET is not valid for systems controlled by the Field System (eg MarkIV and varients).
This is different from the real time transfer controlled by DATAPATH.
If GRABTO is NONE, which is the default, no data will be written and the other GRAB.. parameters will be ignored.
Note that GRABTIME determines what segment of data is sent. GRABGAP determines what amount of time needs to be set aside to grab the data from the VLBI disk (ftp transfer can happen during the next scan).