This cluster provides deferred classes that abstract out component behaviour:

• CODE is the interfave of the tools/code component. It represents a code element (either an expression or an instruction). Note that each code is either an instruction or an expression (see below). The classes in the tools/code component are intended to be inserted rather than inherited (they add specific behaviour to some instructions and expressions).
• EXPRESSION is the interface of the tools/expression component. It represents an Eiffel expression, i.e. a syntactic construction having a result type.
• INSTRUCTION is the interface of the tools/instruction component. It represents an Eiffel instruction.
• PARSER is the interface of the tools/parser component. It parses a file (an Eiffel file, an ACE file or a configuration file) and extracts syntactic information.
• RUN_FEATURE is the interface of the tools/run_feature component. It represents a live feature, i.e. a callable feature tailored for some particular LIVE_TYPE.
• TYPE_MARK is the interface of the tools/type_mark component. It represents an Eiffel type.

Moreover, the class SMART_EIFFEL drives the compilation process. It stays in this cluster because it is so important.