spec: add more abbreviations

README.md

@@ -22,20 +22,24 @@ octave 2
 play c
 play d
 play e
-off
+channel 1 { set nF5; trigger }
+off; wait beat
 
 play c
 play d
 play e
-off
+channel 1 { set nG5; trigger }
+off; wait beat
 
 play c
 play d
+channel 1 { set nF5; trigger }
 play e
-off
+channel 1 { set nG5; trigger }
+off; wait beat
 
 play b
-off
+off; wait beat
 ```
 
 ### Values
@@ -47,7 +51,7 @@ or **absolute** like like `C2`, `Ab4`, or `F#0`.
 Where a note value is needed, a voltage value (as below) can be substituted, prefixed with a `v`, like `v12c`.
 
 - Voltage values, which can be expressed in volts (like `2v`), millivolts
-(like `2330mv`), cents (like `220c`), semitones (like `4c`), or octaves (like `1o`), and which can be **absolute** or **relative** (like `+2c`).
+(like `2330mv`), cents (like `220c`), semitones (like `4s`), or octaves (like `1o`), and which can be **absolute** or **relative** (like `+2c`).
 Where a voltage value is needed, a note value (as above) can be substituted, prefixed with an `n`, like `n2C#`.
 
 - Conf(iguration) values, which are used to set up channel parameters,
@@ -79,9 +83,9 @@ very short time, then turns it off.
 
 ### Channel Control
 
-- `channel <int>` sets the channel currently being controlled.
+- `channel <int> [{ <commands> }]` (abbr. `c`) sets the channel currently being controlled, or executes the given commands on the given channel.
 
-- `octave <int>` sets the octave, between 0 and 8, to which simple and relative note values will be played.
+- `octave <int>` (abbr. `v`) sets the octave, between 0 and 8, to which simple and relative note values will be played.
 
 - `bpm <natural>` sets the tempo of the channel. This is the time used by the time value `beat` and by the `play` instruction.