| ERROR | A subprogram body must be defined for the forward declaration of string. |
| CAUSE | A subprogram specification was declared, but the corresponding subprogram body was not defined. Write the subprogram specification and body as a unit. An alternative solution is to separate the specification from its body, which is necessary when you want to define mutually recursive subprograms or you want to group subprograms in a package. |
| ACTION | Check the spelling of the subprogram name. If necessary, supply the missing subprogram body. |