Sentence:  How the guitarist chooses to create the differences between the accented and unaccented notes has usually been left up to the player, although it is usual for players to use a <WSD>downstrike</WSD> (apoyando) for an accented tone and an upstroke (tirando) for an unaccented tone. 
Meaning of the word marked with <WSD> tags:  A downward plucking motion on a stringed instrument.