Substitution Variable Expansion

When a substitution variable reference is replaced by a variable setting value, the value is recursively expanded before being substituted. This expansion is necessary because the value itself might contain references to simple substitution variables. To prevent the substitution of values, escape input sources with :[[.

You can only use host and external component substitution references in default or override substitution values, parameter default values, and local variable default values. Such references are not permitted in other input sources.