Extended Sustains

Extended sustains are a mechanic in Guitar Hero that allow players to hit notes higher than the sustain they are holding (a red note beside a green sustain while the green sustain is playing), without the sustain cutting off.

In Guitar Hero III, extended sustains can be played, but only just. The player cannot press a button that is higher than the sustain they are holding (plus lower if they're holding a chord sustain). So to play extended sustains, the notes must be INSIDE the sustain (preferably the highest note (e.g. Blue note in a Green and Blue sustain)) to prevent the sustain from cutting off.

How it works
Usually, when a sustain is hit, there is logic set to detect for any wrong frets. If the wrong frets are pressed, the sustain will drop. If the game detects extended sustains in the chart, it ignores this logic (from Guitar Hero World Tour and onwards).

Trivia

 * It is possible to play extended sustains in the early Guitar Hero games (such as GH1 and GH80's, due to the broken HOPO engine).
 * People who have seen these before most likely watched Guitar Hero III custom song videos, as some customs use them a lot.
 * The only song in GH:SE to have extended sustains (before V9) is Uber Song, which has an extended sustain near the ending solo, which isn't possible to hit. This was put in unintentionally by the creator (Lawrence), as he didn't look into the right values for each sustain length.