address comments

kainino0x · kainino0x · commit 40d7b4e53611 · 2021-04-15T14:23:46.000-07:00
diff --git a/explainer/index.bs b/explainer/index.bs
@@ -819,16 +819,17 @@ Issue: Update both names to whatever we settle on.
 
 ### GPUExternalTexture ### {#image-input-external-texture}
 
-A `GPUExternalTexture` is a read-only texture object which can be used in similar ways to normal
-`GPUTexture` objects.
+A `GPUExternalTexture` is a sampleable texture object which can be used in similar ways to normal
+sampleable `GPUTexture` objects.
 In particular, it can be bound as a texture resource to a shader and used directly from the GPU:
 when it is bound, additional metadata is attached that allows WebGPU to "automagically"
 transform the data from its underlying representation (e.g. YUV) to RGB sampled data.
 
-`GPUExternalTexture`s represent a particular immutable image, so the underlying data must not
-change after import. To achieve this:
+A `GPUExternalTexture` represents a particular imported image, so the underlying data must not
+change after import, either from internal (WebGPU) or external (Web platform) access.
 
-Issue: Describe how this works for video element, VideoFrame, canvas element, and OffscreenCanvas.
+Issue:
+Describe how this is achieved for video element, VideoFrame, canvas element, and OffscreenCanvas.
 
 
 ## Canvas Output ## {#canvas-output}
