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

[Karl Berry]

       \fontencoding just prepares the change to come, and \selectfont does it.

MHO:
\fontencoding prepares for the change, and \selectfont does it.

    PS: I think it would be good to examplify this by some example

Examples are good. --thanks, karl.