QUOTE from G-70 manual:

......the Cover functions first introduced on Roland’s
unique DisCover 5 keyboard…

COVER button:
This button provides access to pre-programmed templates
that allow you to quickly modify a song’s or
Music Style’s character.

Style Cover :
30 ALL Covers
18 Drum Covers
24 Bass Covers

Cover functions and Makeup Tools for Standard
MIDI Files and Music Styles:
Reorchestrating existing Standard MIDI Files and Music
Styles has become a breeze thanks to high-quality Song
and Style Cover presets and an intuitive, instrumentbased,
set of MAKEUP TOOLS parameters that allow you
to “revoice” your songs and Styles without spending
hours editing single events.
The structure of Standard MIDI Files can be changed in
real-time thanks to four programmable MARK & JUMP
memories, which allows you to play extended versions
of prerecorded songs.

Song Cover function:
The COVER function provides “masks” that change the
instrumentation of the selected song (or Music Style).
Simply by selecting another preset, you can cause a
Viennese waltz to be played back by a heavy metal
band, etc. Even though the arrangement (rhythm, riffs)
does not change, the songs’ character can be modified
beyond recognition.

Style Cover function:
The COVER function provides “masks” that change the
instrumentation of the selected Style. Simply by selecting
another preset, you can cause a Viennese waltz to
be played back by a heavy metal band, etc. Even though
the arrangement (rhythm, riffs) does not change, the
Style’s character can be modified beyond recognition.

End QUOTE


Hope this lines from the manual give some answers to your
question.

Cheers
GJ