What is the difference between “rich text” and “plain text”?
Rich text is text with all its formatting information: typeface, point size, weight, kerning, and so on. Plain text is the underlying content stream to which formatting is applied. One key distinction between the two is that rich text breaks the text up into runs and applies uniform formatting to each run. As such, rich text is inherently stateful. Plain text is not stateful. It should be possible to lose the first half of a block of plain text without any impact on rendering. Unicode, by design, only deals with plain text. It doesn’t provide a generalized solution to rich text issues.
