It is the sustain with the damper held.
Traditionally a sustain type voice (strings, organ, flute, etc) would
sustain for as long as you held the damper. Since PSR2000
remember correctly) the sustain voices decay in a manner similar to piano, when the damper is held and the key is released. There is an exception, XG sustain voices continue to sustain indefinitely. This is by design.
To use your XG voices:Yes the T2 has XG voices. To access them


1. Go to any voice category

2. Press the UP button

3. Go to page 2

4. Choose GM/XG

5. Choose your voice category

6. Choose your voice