Why Baudot (the ITA2 code used in traditional amateur RTTY) represents each character with just 5 data bits, framed by a start bit and a stop bit for asynchronous timing. Five bits only give 32 combinations, so Baudot uses LTRS and FIGS shift characters to switch between letters and figures. It carries no parity and no error correction, so a hit by noise simply prints the wrong character.
Watch out The 7-bit code with start, stop and parity bits describes ASCII, and the error detecting/correcting mode with SELCAL is AMTOR, not Baudot.
Baudot = 5 bits (B-a-u-d-o-t, five letters after the B? just remember 5-bit RTTY); ASCII = 7-bit.