This information is part of the Modelica Standard Library maintained by the Modelica Association.
Define specialized class block
block Integrator input Real u; output Real y; protected Real x; equation der(x) = u; y = x; end Integrator;
[ encapsulated ][ partial ] block IDENT class_specifier class_specifier : string_comment composition end IDENT | "=" base_prefix name [ array_subscripts ] [ class_modification ] comment | "=" enumeration "(" ( [enum_list] | ":" ) ")" comment
See Modelica Language Specification for further details.
A block class is the same as a model class with the restriction that each connector component of a block must have prefixes input and/or output for all connector variables. The purpose is to model input/output blocks of block diagrams. Due to the restrictions on input and output prefixes, connections between blocks are only possible according to block diagram semantic.