diff --git a/src/SUMMARY.md b/src/SUMMARY.md
index a6ddda9..cf064f1 100644
--- a/src/SUMMARY.md
+++ b/src/SUMMARY.md
@@ -38,6 +38,7 @@
   - [Implementation]()
     - [Audio effects](octavia/impl/efx.md)
     - [RPN/NRPN](octavia/impl/pn.md)
+    - [Voice map format](octavia/impl/maps.md)
   - [Support]()
     - [Specs](octavia/support/implementation.md)
     - [SysEx](octavia/support/sysex.md)
diff --git a/src/octavia/impl/maps.md b/src/octavia/impl/maps.md
new file mode 100644
index 0000000..74d194c
--- /dev/null
+++ b/src/octavia/impl/maps.md
@@ -0,0 +1,66 @@
+# Voice data maps
+## Types
+### ID maps
+TSV files mapping MSB, PRG and LSB into voices.
+
+- `MSB`: cc0 (bank MSB) value of the voice.
+- `PRG`: PC (program change) value of the voice.
+- `LSB`: cc32 (bank LSB) value of the voice.
+- `NME`: 8-character ID of the voice.
+- `ELC`: Element count (minus one) of the voice.
+  - When set to `0`, the voice takes up one element. `1` for two, `2` for three, the same goes on.
+  - When set to `16`, the voice is treated as a drum kit.
+  - When set to `17`, the voice is treated as a voice menu.
+  - Any value above is not defined.
+- `DRM`: Drum map ID used. Can also be used by voice menus.
+- `VXP`: Voice property map ID used.
+
+### Drum maps
+Custom script files defining properties of drum kits and their voices.
+
+- `drm` defines the current drum map ID to write to.
+  - e.g. `drm xgStdKit` switches to `xgStdKit`.
+- `dcp` copies parameters from a set drum kit.
+  - e.g. `dcp xgStdKit` copies parameters from `xgStdKit` to the current drum kit.
+- `nno` defines the current drum note number to write to.
+  - e.g. `nno 39` switches to `39`.
+- `npw` writes multiple parameters to a single drum note.
+  - `npw <note> <exclusiveGroup> <elementCount>`
+- `neg` sets the exclusive group (aka. alternate assign) of the current note number. Defaults to `0` (disabled).
+- `nec` sets the note element count of the current note number. Defaults to `1`.
+
+### Voice property maps
+TSV files describing certain properties of individual voices.
+
+#### VL properties
+- `BNS`: VL Breath Noise Source
+  - `0`: None
+  - `1`: Modulation wheel
+  - `2`: Blow strength
+  - `3`: Blow strength + throat formant
+- `BAD`: VL Breath Attack Duration, specified in milliseconds
+- `BAL`: VL Breath Attack Level
+  - `0`: -64 (from a very wide triangle)
+  - `64`: 0 (no attack EG)
+  - `127`: 63 (from a very narrow triangle)
+- `BDD`: VL Breath Decay Duration, specified in milliseconds
+- `BDL`: VL Breath Decay Level
+  - `0`: Decay to 0 (pluck)
+  - `64`: Decay to 50.4%
+  - `127`: No decay
+- `TOM`: VL Throat Formant Oscillation from Modulation
+  - `0`: None
+  - `127`: Maximum
+- `TOS`: VL Throat Formant Oscillation Speed, specified in milliseconds when a cycle completes.
+- `TOT`: VL Throat Formant Oscillation Type
+  - `0`: None
+  - `1`: Single oscillator
+  - `2`: Double oscillator (single oscillator modulated by an additional LFO)
+- `TFS`: VL Throat Formant Source
+  - `0`: Constant until set
+  - `1`: cc1 (Modulation wheel)
+  - ...
+  - `13`: cc13 (default VL throat formant source)
+  - ...
+  - `32`: Always constant
+- `TFV`: VL Throat Formant Value, the fixed default value for certain instruments.
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