diff --git a/doc/4-instrument/pet.md b/doc/4-instrument/pet.md
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+# Commodore PET instrument editor
+
+The PET instrument editor consists of these macros:
+
+- **Volume**: volume sequence (on/off)
+- **Arpeggio**: pitch sequence
+- **Waveform**: 1-bit polynomial pattern type sequence
+- **Pitch**: "fine" pitch
diff --git a/doc/4-instrument/vic.md b/doc/4-instrument/vic.md
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+# Commodore VIC instrument editor
+
+The VIC instrument editor consists of these macros:
+
+- **Volume**: volume sequence (GLOBAL)
+- **Arpeggio**: pitch sequence
+- **On/off**: enable/disable channel output
+- **Waveform**: square wave distortion type sequence
+- **Pitch**: "fine" pitch