Commodore 128 System Manual page 151

You have the option of specifying the duration of the note by
preceding it in quotes with one of the following notations:
W —
Whole note
H —
Half note
Q
— Quarter note
I — Eighth note
S
— Sixteenth note
The default setting, if the duration is not specified, is for Whole
(W) notes.
You can PLAY a rest by including the following in the PLAY
string:
R
— Rest
You can instruct the computer to wait until all voices currently
playing reach the end of a measure by including the following in
quotes:
M —
Wait for end of measure
The Commodore 128 also has synthesizer control characters you
can include in a PLAY string. This gives you absolute control over
each note and allows you to change synthesizer controls within a
string of notes. Follow the control character with a number in the
allowable range for that character. The control characters and
the range of numbers for each are shown in Figure 7-6. The " n"
following the control character refers to the number you select
from the specified range.
Control
Character
V n
0 n
T n
U n
X n
Figure 7-6. Sound Synthesizer Control Characters
Although the SID chip can process these control characters in
any order, for the best results, place the control characters in
your string in the order that they appear in Figure 7-6.
Description
Voice
Octave
Envelope
Volume
Filter
Range
1-3
0-6
0-9
0-15
0=off
1=on
Default
Setting
1
4
0
9
0
7-17