diff --git a/implementations/rust/preserves-schema/Cargo.toml b/implementations/rust/preserves-schema/Cargo.toml
index c4ab2d7..153382d 100644
--- a/implementations/rust/preserves-schema/Cargo.toml
+++ b/implementations/rust/preserves-schema/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "preserves-schema"
-version = "3.990.0"
+version = "3.990.1"
 authors = ["Tony Garnock-Jones <tonyg@leastfixedpoint.com>"]
 edition = "2018"
 description = "Implementation of Preserves Schema code generation and support for Rust."
diff --git a/implementations/rust/preserves/Cargo.toml b/implementations/rust/preserves/Cargo.toml
index 3d1df3a..95adf9c 100644
--- a/implementations/rust/preserves/Cargo.toml
+++ b/implementations/rust/preserves/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "preserves"
-version = "3.990.0"
+version = "3.990.1"
 authors = ["Tony Garnock-Jones <tonyg@leastfixedpoint.com>"]
 edition = "2018"
 description = "Implementation of the Preserves serialization format via serde."
diff --git a/implementations/rust/preserves/doc/value-grammar.md b/implementations/rust/preserves/doc/value-grammar.md
new file mode 100644
index 0000000..5ad8fde
--- /dev/null
+++ b/implementations/rust/preserves/doc/value-grammar.md
@@ -0,0 +1,18 @@
+```text
+                      Value = Atom
+                            | Compound
+                            | Embedded
+
+                       Atom = Boolean
+                            | Float
+                            | Double
+                            | SignedInteger
+                            | String
+                            | ByteString
+                            | Symbol
+
+                   Compound = Record
+                            | Sequence
+                            | Set
+                            | Dictionary
+```