add edits, incorporate feedback from RFC comments

Author: monicadsong

rfcs/20220610-saved-model-fingerprinting.md

@@ -9,7 +9,7 @@
 
 ## Objective
 
-Following the convention of other types of electronic files and artifacts, the SavedModel format would benefit from having a fingerprint that uniquely identify the program it serializes. This fingerprint will better enable users to track their SavedModels in ML pipelines and other infrastructure using native metadata.
+Following the convention of other types of electronic files and artifacts, the SavedModel format would benefit from having a fingerprint that uniquely identify the program it serializes.
 
 ## Motivation
 
@@ -201,7 +201,7 @@ We can also explore the option of adding a Python API such as `tf.saved_model.ch
 
 The fingerprinting will be added as a final step of serialization. The fingerprint infrastructure will take as input the MetaGraphDef and hash each component of it, doing the necessary regularization as well.
 
-The hashing will occur in C++, since it is easier to find an open source hashing algorithm in C++ than in Python. Hashing in C++ is also much faster. There will be pybinded wrappers for access from Python. This will require passing the protobuf across the Python and C++ boundary which may require an extra cycle of de/serialization.
+The hashing will occur in C++, since it is easier to find an open source hashing algorithm in C++ than in Python. There will be pybinded wrappers for access from Python. This will require passing the protobuf across the Python and C++ boundary which may require an extra cycle of de/serialization.
 
 ### Launch Plan
 
@@ -247,6 +247,13 @@ When creating the SavedModel proto, we’d collect the fingerprints of each of t
 
 The disadvantage of this approach is that it is primarily in Python and works with the objects as defined in Python. Working in C++ is preferable to working in Python.
 
+#### Text Format Proto
+
+One idea is have the fingerprint be in [text format](https://developers.google.com/protocol-buffers/docs/text-format-spec) so it
+can be human-readable. However, the disadvantage is that using text format prevents us from making changes to the fields in the
+fingerprint protobuf. Text format is not designed with the same forward- and backward-compatibility properties as the binary format, so
+we avoid using it with production infrastructure.
+
 ### Future Ideas
 
 #### Changes to the CLI