Paper tape punched with holes in a pattern that can be read by a machine as data is a storage technique that never really made it into the mainstream, but was used at times in the 1950s and 1960s. Unlike punch cards which feature a large grid for data, the perforated paper tape had only five or six rows. Tape was 0.1mm thick and one inch wide. The patterns that developed for punching data codes into the paper was a rudimentary form of ASCII. Though punched paper tape had a few advantages (namely, it could be read by a trained human eye, could be easily destroyed for security purposes, and was undamaged if left for long periods in rooms with lots of strong magnetic fields), the punched tape took up too much space and tore easily. This fragility and low space efficiency helped pave the way for magnetic tape.