1 files changed, 8 insertions, 1 deletions
diff --git a/src/core/transport/stream_op.h b/src/core/transport/stream_op.h
index 5215cc87b1..e080701e2d 100644
--- a/src/core/transport/stream_op.h
+++ b/src/core/transport/stream_op.h
@@ -58,11 +58,18 @@ typedef enum grpc_stream_op_code {
   GRPC_OP_SLICE
 } grpc_stream_op_code;
 
+/** Internal bit flag for grpc_begin_message's \a flags signaling the use of
+ * compression for the message */
+#define GRPC_WRITE_INTERNAL_COMPRESS (0x80000000u)
+/** Mask of all valid internal flags. */
+#define GRPC_WRITE_INTERNAL_USED_MASK (GRPC_WRITE_INTERNAL_COMPRESS)
+
 /* Arguments for GRPC_OP_BEGIN_MESSAGE */
 typedef struct grpc_begin_message {
   /* How many bytes of data will this message contain */
   gpr_uint32 length;
-  /* Write flags for the message: see grpc.h GRPC_WRITE_xxx */
+  /* Write flags for the message: see grpc.h GRPC_WRITE_* for the public bits,
+   * GRPC_WRITE_INTERNAL_* for the internal ones. */
   gpr_uint32 flags;
 } grpc_begin_message;