[circle-schema] Add MX dtype restrictions comment

This commit adds comprehensive comments documenting current restrictions for MX dtypes (MXFP4, MXINT8) in the circle schema.

ONE-DCO-1.0-Signed-off-by: Hyeongseok Oh <hseok82.oh@samsung.com>

Author: hseok-oh

nnpackage/schema/circle_schema.fbs

@@ -87,6 +87,11 @@ enum TensorType : byte {
   GGML_Q8_1 = -5,
 
   // MX dtypes
+  // Current restrictions of MX dtypes
+  // - MX dtypes are not used for model I/O
+  // - MX dtypes are used for activations, not for constant inputs (ex. weight)
+  // - Model does not have MX dtype's parameters (block size, exponent scale, etc).
+  //   Backend should define and use internally if needed
   MXFP4 = -6,
   MXINT8 = -7,
 }

res/CircleSchema/0.10/circle_schema.fbs

@@ -87,6 +87,11 @@ enum TensorType : byte {
   GGML_Q8_1 = -5,
 
   // MX dtypes
+  // Current restrictions of MX dtypes
+  // - MX dtypes are not used for model I/O
+  // - MX dtypes are used for activations, not for constant inputs (ex. weight)
+  // - Model does not have MX dtype's parameters (block size, exponent scale, etc).
+  //   Backend should define and use internally if needed
   MXFP4 = -6,
   MXINT8 = -7,
 }

runtime/libs/circle-schema/circle_schema.fbs

@@ -87,6 +87,11 @@ enum TensorType : byte {
   GGML_Q8_1 = -5,
 
   // MX dtypes
+  // Current restrictions of MX dtypes
+  // - MX dtypes are not used for model I/O
+  // - MX dtypes are used for activations, not for constant inputs (ex. weight)
+  // - Model does not have MX dtype's parameters (block size, exponent scale, etc).
+  //   Backend should define and use internally if needed
   MXFP4 = -6,
   MXINT8 = -7,
 }