Triggers the use of multiple phase center processing on the DiFX correlator at least at the VLBA. In practice, this puts the list of phase centers in the .v2d file used in setting up correlation. Some day, it may put the list in the .vex file, if there is a standard for how to do that.
The argument of CENTERS must correspond to a list of names in the phase center groups listed after a PCENTERS command.
For now, there is no clear way to make the phase center list scan dependent, so specify the same name for each scan on the same source. This may not always be true, which is why the association of a phase center group with a pointing source is not done in the PCENTERS specifications.
For more information on multiple phase center processing, see that section about that topic.