This option indicates whether additional renaming should be done when symbols remain unresolved. Unresolved function references that are marked as renameable and are not imported are set to uppercase if they are eight characters or less in length. Also, underscore ('_') is mapped to '@' and names beginning with IBM®, CEE, or PLI have their respective prefixes changed to IB$, CE$, and PL$. After the renaming process is complete, an attempt to resolve the symbols using the new names is made. Traditional object modules do not support the renameable bit and thus symbols originating from them are not affected by the UPCASE option.

The UPcase option provides binder function roughly equivalent to the prelinker UPCASE option.