The Text/Plain Format and DelSp Parameters
This specification establishes two parameters (Format and DelSP) to be used with the Text/Plain media type. In the presence of these parameters, trailing whitespace is used to indicate flowed lines and a canonical quote indicator is used to indicate quoted lines. This results in an encoding which appears as normal Text/Plain in older implementations, since it is in fact normal Text/Plain, yet provides for superior wrapping/flowing, and quoting. This document supersedes the one specified in RFC 2646, "The Text/Plain Format Parameter", and adds the DelSp parameter to accommodate languages/coded character sets in which ASCII spaces are not used or appear rarely. [STANDARDS-TRACK]