The architecture describes mandatory interfaces that must be available on all implementations, and optional interfaces. Different translation proxy implementations have different capabilities. Traits can be seen as interfaces carrying both default implementations and state. Echo cancelers are available as both software and hardware implementations. Animal interface is the key to compatibility for Animal implementations below. It also has its own protocol implementations. The website includes verification data for testing core implementations. The EIA-232 standard specifies connections for several features that are not used in most implementations. GoboLinux and NixOS provide examples of intentionally non-compliant filesystem implementations. It was created to standardize JavaScript to help foster multiple independent implementations. The cost of computation involved in naive Galerkin implementations is typically quite severe. They are useful to define a contract with any number of different implementations. Various companies have attempted to claim patents for specific aspects of syslog implementations. Thus many vendors had to issue patches for their SNMP implementations. LINQ provides a capability over typical List Comprehension implementations.