A standard (SPN/004) PORT binary table extension is recorded in order to allow the CCB inputs to be cross-indexed with the physical descriptions provided in the IF manager IF table. There are two columns: BANK (a character), and PORT (a non-zero integer). A given value of PORT uniquely identifies a physical input to the CCB, and may be used to index physical descriptions (frequency, feed, polarization ,etc) in the IF manager IF table. It also uniquely defines a row in the PORT table. The BANK column is retained for compliance with the GBT FITS standard and are set to a fiducial value of 'A'.
Additionally there is a SLAVE column indicating which daughter card a given input port is associated with. Data are unsigned 8-bit integers with valid values 0,1,2,3.
The order of the rows of the PORT table correspond to the ordering of PORT columns in the DATA table. The number of rows NPORTS of the PORT table is equal to the number of ports input ports selected as active in the manager for the given scan.