Limitation of Editor:
Link between '<DS:URLA.' and 1st '>' MUST lay on the same line. The size of line is 72, so if you count 72-10=62 symbols are max allowed by Editor. So it does not have sense for our application to touch any dictionary declaration in case of URLA-class.
In general, changing class-interfaces and declaration of tables / structures is not allowed in releases with support package delivery and 7.01 is a such release. You can find all affected places via Where-used list of affected domain or data element DOKU_OBJ. It was a reason why this small extending have been done only from 7.10 release and for 7.03 release.
As workaround, you can create a report with 1 short parameter and use link type 'Online execution of a report with parameter selection' in SE61-Editor. The URLs, assigned to provided parameter, should be either kept in some table or hardcoded. In this case, report can select correct URL and dispaly it by using methods of class CL_GUI_FRONTEND_SERVICES.