Some components allow parameterization of configuration at runtime, for example, connectivity plug-in chains created from a manager or from EPL. Variables which must be replaced at runtime are denoted with @{varname} instead of ${varname}. Strings using this syntax may need to be escaped with double quotes in the YAML configuration file. Instead of being supplied via the command line or via properties files, these substitutions are provided within the subsystem using that part of the configuration. See also Creating dynamic chains from EPL.