Invalid shelf declaration encountered.

#2077 Compile-time error

Invalid shelf declaration encountered.

Additional Information

The predefined X "Y" may not be redeclared.
    where X is the type of the shelf, Y its name.
    or
The shelf X "Y" has already been declared as type Z in the same scope.
    or
Local X "Y" is already declared in the current scope.
    or
Global X "Y" is already declared.

Recovery

Compilation continues but no compiled source code file will be saved.

Explanation

The predefined shelves (the ones starting with a '#') may never be declared.

Unless the program is using heralded names, two variables of different types may not be declared in the same scope (either both global, or both at the same level as a local). With version 5.4, a global variable may not be declared more than once.