 The matrix number appeared on the label, usually upside-down directly beneath the main catalogue number.The matrix numbers seem to have been allocated to each release in numerical sequence, irrespective of the actual or proposed release date of the record; thus the two sides of WIP-6056 (Jethro Tull's "Living In The Past" b/w "Driving Song") have matrix numbers wipx 1010 and wipx 1011, respectively.Initially, the new matrix numbers were used in conjunction with the existing "eye" label design, but beginning with releases in June 1969 a new pink label design was introduced, known as the "block" design.