A process in which data, printed in ink containing ferromagnetic particles, is read by magnetic read heads. The shape of the characters resembles those of normal typescript but each generates a unique signal as it is scanned by the read head. The most common application is for encoding numbers on bank checks.

There are two standardized fonts: the E13B and CMC7. The E13B font is very rectangular in appearance and some parts of the vertical limbs may be thickened to accentuate the difference in the generated wave form. This font is widely used in the US and the UK. The CMC7 font has the character shape sliced into seven vertical strips with the six intervening spaces either wide or narrow. Each of the numerical symbols and the four special symbols is coded with a combination of two wide and four narrow spaces.