
WRITEL  For writing labeled tapes.  Asks the following:

        Tape Name:
                The name of the tape, with colon after it.

        Format  One of: D, F, S, or U:

                F  -  fixed  size records.  All lines are filled with blanks to
                        make them the same size.    This  format  is  the  most
                        likely  to  be supported by other computers, but wastes
                        space if lines are of different lengths.  If all  lines
                        are the same length, this is the best.

                D  -  variable  size  records.   Lines are not filled.  Special
                        control information is used to show how long each  line
                        is.    This  is  more  efficient  if lines of different
                        lengths.  However IBM systems can't read this format.

                S - spanned records.  A slight variant of format D,  for  files
                        with  extremely  long  lines.  Allows lines to be split
                        across  physical  record  boundaries.    This  is  more
                        efficient  for  very  long  lines, but takes a bit more
                        processing overhead, and  is  supported  by  few  other
                        computer systems.

                U  -  undefined.  Puts each line in a separate physical record.
                        This is unlikely to  be  supported  by  other  computer
                        systems,  and  also  wastes space, unless the lines are
                        very big.

                Generally we recommend format F if lines are  nearly  the  same
                length  or  if you need to be able to move the tape to the most
                possible different computers.  Format D would be used for files
                with lines  of  very  different  lengths,  if  you  are  mostly
                concerned with DEC computers.

        Record size:
                This  is  the size of the longest line in the file.  For format
                F, all lines will be filled to this length with  blanks.    For
                other formats, it should be a number that is known to be larger
                than  the  largest  line in the file.  (The exact value doesn't
                matter much.)

        Block Size:
                This may or may not be asked, depending upon  the  format.  The
                block  size  is  the size of the physical records on tape. More
                than one line (logical record) may be packed into one  physical
                record.    The  advantage  of packing into large records is the
                there is a .5 inches of space  wasted  on  the  tape  for  each
                record.  So if you put many lines in one record, you waste less
                space  for  a given file.  The maximum block size is 32768. For
                1600 bpi tapes, a block size around 6000 is helpful.  For  6250
                bpi tapes, something near the maximum is probably a good idea.

                   - For  format  F,  the  actual  question  is  "how many
                     records per block". The block size in  this  case  is
                     the  record  size  times  the  number  of records per
                     block.

                   - For format D and S, you  are  asked  to  specify  the
                     block size directly.

                   - For format U, this question is not applicable.

        Copy From:
                This is the name of the disk file to copy to the tape.  You may
                use wildcards.  The program will keep asking this question.  ^C
                when you have written all the data you want to write.
