OK, I've changed the "Justification Commands" section to look like this
-- comments welcome.
Fill/Justification Commands
Initially, text/enriched text is intended to be displayed fully filled
with appropriate kerning and letter-tracking as suits the capabilities
of the receiving user agent software. Actual line width is left to the
discretion of the receiver, which is expected to fold lines
intelligently (preferring soft line breaks) to the best of its ability.
The following commands alter that state. Each of these commands force a
line break before and after the formatting command if there is not
otherwise a line break. For example, if one of these commands occurs
anywhere other than the beginning of a line of text as presented, a new
line is begun.
Center -- causes the affected text to be centered.
FlushLeft -- causes the affected text to be left-justified with
a ragged right margin.
FlushRight -- causes the affected text to be right-justified
with a ragged left margin.
Nofill -- causes the affected text to be displayed without
filling or justification.
The center, flushleft, and flushright commands are mutually exclusive,
and, when nested, the inner command takes precedence.
Whether or not text is justified by default (padded to create a smooth
right margin) is unspecified, and depends on the capabilities of the
local software and hardware and the tastes of the implementors.
However, justification should not be performed inside of center,
flushleft, flushright, or nofill environments. Note also that for some
non-ASCII character sets, full justification may be fundamentally
inappropriate.