Reasoning behing 76 being the line length limit for MIME sections, as defined by RFC 2045?

Question

RFC 2045 defines the maxmimum line length for encoded data as 76 - however I cannot find any explanation as to why it is 76. Is this number entirely arbitrary, or is there s

Answer 1

The bit to do with user interfaces

http://en.wikipedia.org/wiki/Text_mode#PC_common_text_modes

Basically, 80 characters across (and usually 25 or 30 lines) was the most common standard for displays. 78 provides a sane standard as this allows for some small decorations to be used (borders).