[CLEAN\]READ Buffer File /NOTRAIL [/FREQUENCY Freq] [/RANGE Min Max Type] When reading UV Tables, ignores any trailing column. Trailing columns normally appear for mosaics. However, ALMA sometimes uses known proper motions to shift (by small amounts) phase centers between two observing periods, yielding pseudo-mosaics with tiny (in general insignificant) displacements. The /NOTRAIL option allows to ignore these details.