diff --git a/dsdl/uavcan/protocol/file/218.Read.uavcan b/dsdl/uavcan/protocol/file/218.Read.uavcan
index c7a54724fa..b120a86301 100644
--- a/dsdl/uavcan/protocol/file/218.Read.uavcan
+++ b/dsdl/uavcan/protocol/file/218.Read.uavcan
@@ -1,11 +1,15 @@
 #
-# Read contents of the file from remote node.
-# Empty data in response means that the offset is out of file boundaries.
-# Non-empty data means the end of file is not reached yet, even if the length is less than maximum.
+# Read file from a remote node.
+# 
+# There are two possible outcomes of a successful service call:
+#  1. Data array size equals its capacity. This means that the end of the file is not reached yet.
+#  2. Data array size is less than its capacity, possibly zero. This means that the end of file is reached.
+# 
 # Thus, if the client needs to fetch the entire file, it should repeatedly call this service while increasing the
-# offset, until the empty data is returned.
+# offset, until incomplete data is returned.
+#
 # If the object pointed by 'path' cannot be read (e.g. it is a directory or it does not exist), appropriate error code
-# will be returned.
+# will be returned, and data array will be empty.
 #
 
 uint32 offset
@@ -14,4 +18,4 @@ Path path
 ---
 
 Error error
-uint8[<=250] data
+uint8[<=256] data