<value specification> ::=
<parameter specification>
| <variable specification>
| <literal>
| USER
<target specification> ::=
<parameter specification>
| <variable specification>
<parameter specification> ::=
<parameter name> [<indicator paremeter>]
<indicator parameter> ::=
[INDICATOR] <parameter name>
<variable specification> ::=
<embedded variable name> [<indicator variable>]
<indicator variable> ::=
[INDICATOR] <embedded variable name>