The format of an entry is :-

%record %format entryf (%record (entryf) %name next, previous,  { pointers }
                        %integer start, finish,  {address limits of mapping }
                        %short channel,  {file access channel}
                        %integer crmpsc flags,
                        %byte %array fib stuff (0:39),
                        %byte spare1, spare2,   {available for you}
                        %integer length,   {of the file in bytes}
                        %string(<127) filename)