Page "ASCII" Paragraph 16

With the other special characters and control codes filled in, ASCII was published as ASA X3. 4-1963, leaving 28 code positions without any assigned meaning, reserved for future standardization, and one unassigned control code.

There was some debate at the time whether there should be more control characters rather than the lower case alphabet.

The indecision did not last long: during May 1963 the CCITT Working Party on the New Telegraph Alphabet proposed to assign lower case characters to columns 6 and 7, and International Organization for Standardization TC 97 SC 2 voted during October to incorporate the change into its draft standard.

The X3. 2. 4 task group voted its approval for the change to ASCII at its May 1963 meeting.

Locating the lowercase letters in columns 6 and 7 caused the characters to differ in bit pattern from the upper case by a single bit, which simplified case-insensitive character matching and the construction of keyboards and printers.