[latexrefman] it switches from one encoding to another with the @code{\selectfont} or @code{\fontencoding} command

[Karl Berry]

    My understanding is the \fontencoding does no immediate switching as
    such, 

Yes it does. Maybe not at the user level, I'm not sure what the
visible result is, but in the code the switch is made in \fontencoding.

    it just sets the encoding to which the next \selectfont will
    switch. So ``or'' should be replaced by ``and''.

No it shouldn't.

When I look at the actual definition of \fontencoding (in ltfssbas.dtx),
the "text-setting" commands from \DeclareFontEncoding are executed:

\DeclareRobustCommand\fontencoding[1]{%
..
  \csname T@\f at encoding\endcsname
..
}

The \csname T@\f at encoding\endcsname cs is where the "text-setting"
commands were saved.

At a glance, I do not see them being executed as being part of
\selectfont.

So I suggest doing some experiments to find out the actual facts.
Failing that, I suggest leaving it alone. -k