+# Intro\r
+\r
+This section deals with the following specifications\r
+\r
+* Specification of generic functions applicable in the Simantics framework\r
+* Specification of functions attached to types (methods)\r
+* Specification of functions with side-effects (operations or commands)\r
+* Automatically generated code based on semantic model about functions (stubs)\r
+\r
+## Specification\r
+\r
+* Functions are objects implementing the interface `org.simantics.scl.runtime.function.Function`.\r
+* We have a type `Value` (?) that can be adapted to an SCL value (in particular to a function).\r
+* We have a relation `HasType` (?) Value -> String that specifies the SCL type of the value\r
+* Operations are functions that return an object implementing `WriteResult`.\r