diff --git a/agorata_contracts/src/lib.rs b/agorata_contracts/src/lib.rs
index 061bd89..b050ce8 100644
--- a/agorata_contracts/src/lib.rs
+++ b/agorata_contracts/src/lib.rs
@@ -1,6 +1,9 @@
 extern crate serde;
 
+/// Message and Address types
 pub mod message;
+/// Templating variables.
+pub mod templates;
 
 #[cfg(test)]
 mod tests {
diff --git a/agorata_contracts/src/message.rs b/agorata_contracts/src/message.rs
index 8be9642..a8d571d 100644
--- a/agorata_contracts/src/message.rs
+++ b/agorata_contracts/src/message.rs
@@ -46,5 +46,4 @@ pub struct Message {
     pub amount: i64,
     /// Other currencies.
     pub amounts: Vec<(String, i64)>,
-
 }
diff --git a/agorata_contracts/src/templates.rs b/agorata_contracts/src/templates.rs
new file mode 100644
index 0000000..ff7130a
--- /dev/null
+++ b/agorata_contracts/src/templates.rs
@@ -0,0 +1,97 @@
+use serde::{Deserialize, Serialize};
+use crate::message::Address;
+
+/// Values used for variables in templates.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Value {
+    Int(i64),
+    Bool(bool),
+    Address(Address),
+    Token(Address),
+    Data(Vec<u8>),
+    String(String),
+}
+
+/// Types for variable values.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Copy)]
+pub enum Type {
+    Int,
+    Bool,
+    Address,
+    Token,
+    Data,
+    String,
+}
+
+impl Value {
+    /// Returns the type of the value.
+    pub fn var_type(&self) -> Type {
+        match self {
+            Value::Int(_) => Type::Int,
+            Value::Bool(_) => Type::Bool,
+            Value::Address(_) => Type::Address,
+            Value::Token(_) => Type::Token,
+            Value::Data(_) => Type::Data,
+            Value::String(_) => Type::String,
+        }
+    }
+}
+
+/// Matchers of values
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Matcher {
+    Any,
+    Fixed(Value),
+    NotEqual(Value),
+    Whitelist(Vec<Value>),
+    Blacklist(Vec<Value>),
+    IntRange(i64, i64),
+    Regexp(String),
+}
+
+impl Matcher {
+    /// Check if this is a valid matcher for a given type.
+    pub fn check_correctness_for_type(&self, type_: Type) -> bool {
+        match self {
+            Matcher::Any => true,
+            Matcher::Fixed(v) => v.var_type() == type_,
+            Matcher::NotEqual(v) => v.var_type() == type_,
+            Matcher::Whitelist(v) |  Matcher::Blacklist(v) => {
+                if v.is_empty() {
+                    return false;
+                }
+                // Check that all values are of the same type and that there are no duplicates.
+                if v.iter().any(|v| v.var_type() != type_) {
+                    return false;
+                }
+                let mut v_clone = v.clone();
+                v_clone.dedup();
+                v_clone.len() == v.len()
+            },
+            Matcher::IntRange(i1, i2) => i1 <= i2 && type_ == Type::Int,
+            Matcher::Regexp(_) => type_ == Type::String,
+        }
+    }
+
+    /// Match a value
+    pub fn match_value(&self, value: &Value) -> bool {
+        if !self.check_correctness_for_type(value.var_type()) {
+            return false;
+        }
+        match self {
+            Matcher::Any => true,
+            Matcher::Fixed(v) => v == value,
+            Matcher::NotEqual(v) => v != value,
+            Matcher::Whitelist(v) => v.contains(value),
+            Matcher::Blacklist(v) => !v.contains(value),
+            Matcher::IntRange(i1, i2) => match value {
+                Value::Int(i) => i >= i1 && i <= i2,
+                _ => false,
+            },
+            Matcher::Regexp(_regexp) => match value {
+                Value::String(_s) => todo!(),
+                _ => false,
+            },
+        }
+    }
+}