diff --git a/doc/syntax.md b/doc/syntax.md
index 524053d..932f059 100644
--- a/doc/syntax.md
+++ b/doc/syntax.md
@@ -163,6 +163,8 @@ The function `NOISE(weight, seed)` adds some random noise into the prompt. The s
 
 You can use `MASK(x1 x2, y1 y2, weight, op)` to specify a region mask for a prompt. The values are specified as a percentage with a float between `0` and `1`, or as absolute pixel values (these can't be mixed). `1` will be interpreted as a percentage instead of a pixel value.
 
+Multiple `MASK` or `IMASK` calls will be composited together using ComfyUI's `MaskComposite` node, using `op` as the `operation` parameter (defaulting to `multiply`).
+
 Similarly, you can use `AREA(x1 x2, y1 y2, weight)` to specify an area for the prompt (see ComfyUI's area composition examples). The area is calculated by ComfyUI relative to your latent size.
 
 #### Custom masks: IMASK and `PCAddMaskToCLIP`