diff --git a/mappings/net/minecraft/world/chunk/ChunkNibbleArray.mapping b/mappings/net/minecraft/world/chunk/ChunkNibbleArray.mapping
index 8ac4d26e36..c43981704d 100644
--- a/mappings/net/minecraft/world/chunk/ChunkNibbleArray.mapping
+++ b/mappings/net/minecraft/world/chunk/ChunkNibbleArray.mapping
@@ -1,15 +1,25 @@
 CLASS net/minecraft/class_2804 net/minecraft/world/chunk/ChunkNibbleArray
+	COMMENT A chunk nibble array is an array of nibbles for each block position in
+	COMMENT a chunk. It is most often used to store light data.
+	COMMENT
+	COMMENT <p>A {@index nibble} is 4 bits, storing an integer from {@code 0} to
+	COMMENT {@code 15}. It takes half the space of a byte.
+	COMMENT
+	COMMENT <p>The nibbles are stored in an X-Z-Y major order; in the backing array,
+	COMMENT the indices increases by first increasing X, then Z, and finally Y.
 	FIELD field_12783 bytes [B
 	FIELD field_31403 BYTES_LENGTH I
 	FIELD field_31404 COPY_BLOCK_SIZE I
+	FIELD field_31405 NIBBLE_BITS I
 	METHOD <init> (I)V
 		ARG 1 size
 	METHOD <init> ([B)V
 		ARG 1 bytes
 	METHOD method_12137 asByteArray ()[B
-	METHOD method_12138 divideByTwo (I)I
+	METHOD method_12138 getArrayIndex (I)I
 		ARG 1 n
 	METHOD method_12139 get (III)I
+		COMMENT {@return the integer value of a nibble, in {@code [0, 15]}}
 		ARG 1 x
 		ARG 2 y
 		ARG 3 z
@@ -22,10 +32,26 @@ CLASS net/minecraft/class_2804 net/minecraft/world/chunk/ChunkNibbleArray
 	METHOD method_12142 set (II)V
 		ARG 1 index
 		ARG 2 value
+	METHOD method_12143 occupiesSmallerBits (I)Z
+		COMMENT {@return if the nibble at {@code n} is stored in the less
+		COMMENT significant (smaller) 4 bits of the byte in the backing array}
+		ARG 1 n
+			COMMENT the index of the nibble, not the array index
 	METHOD method_12144 copy ()Lnet/minecraft/class_2804;
 	METHOD method_12145 set (IIII)V
+		COMMENT Sets the value of a nibble.
+		COMMENT
+		COMMENT <p>If the {@code value} has bits outside of the lowest 4 set to {@code 1},
+		COMMENT (value is outside of {@code [0, 15]), the extraneous bits are discarded.
 		ARG 1 x
 		ARG 2 y
 		ARG 3 z
 		ARG 4 value
 	METHOD method_12146 isUninitialized ()Z
+	METHOD method_35320 bottomToString (I)Ljava/lang/String;
+		COMMENT {@return a hexademical string representation of the {@code y=0} level of
+		COMMENT this array}
+		COMMENT
+		COMMENT <p>It is useful for debugging the grid nibble array.
+		ARG 1 unused
+			COMMENT unused
diff --git a/mappings/net/minecraft/world/chunk/GridNibbleArray.mapping b/mappings/net/minecraft/world/chunk/GridNibbleArray.mapping
new file mode 100644
index 0000000000..15a0981cf3
--- /dev/null
+++ b/mappings/net/minecraft/world/chunk/GridNibbleArray.mapping
@@ -0,0 +1,11 @@
+CLASS net/minecraft/class_4298 net/minecraft/world/chunk/GridNibbleArray
+	COMMENT A specialized chunk nibble array that ignores the Y parameters and only
+	COMMENT stores the nibbles for a 16 &times; 16 horizontal chunk slice.
+	COMMENT
+	COMMENT <p>When it is {@linkplain #toByteArray() converted to a byte array}, it
+	COMMENT fills each Y-level of the returned array with the same nibbles it stores.
+	FIELD field_31707 INDICES_PER_Y I
+		COMMENT The number of array indices each Y-level uses in a chunk nibble array.
+	METHOD <init> (Lnet/minecraft/class_2804;I)V
+		ARG 1 array
+		ARG 2 y