tt(INTERNALINDEX) expects one argument list. The argument list is evaluated
and written to the index file.

The index file is defined since Yodl version 2.00, and contains the fixup
information which was previously written to Yodl's output as the
tt(.YODLTAGSTART.  ... .YODLTAGEND.) sequence. 

The index file allows for greater processing speed, at the expense of an
additional file. The associated tt(yodlpost) postprocessing program reads
and processes the index file, and modifies the corresponding yodl-output
accordingly. 

The index file is not created when output is written to the standard output
name, since Yodl is unable to request the system for the current file offset.

The entries of the index file always fit on one line. tt(INTERNALINDEX)
changes newline characters in its argument into single blank spaces. Each line
starts with the current offset of Yodl's output file, thus indicating the
exact location where a fixup is requested. An example of a produced fixup line
could be
        verb(
    3004 ref MACROPACKAGE
        )
    indicating that at offset 3004 in the produced output file a reference to
the label tt(MACROPACKAGE) is requested. Assuming a html conversion, 
The postprocessor thereupon
writes something like 
        verb(
    <a href="outfile04.html#MACROPACKAGE">4.3.2.</a>
        )
    into the actual output file while processing Yodl's output up to 
offset location 3004.

    Consequently, producing Yodl-output normally consists of two steps:
    itemization(
    it() First, Yodl itself is started, producing, e.g., tt(out.idx) (the
index file) and tt(out.yodl) (Yodl's raw output).
    it() Then, Yodl's post-processor processes tt(out.idx) 
and tt(out.yodl), producing one or more final output files, in which the
elements of the index file have been properly handled. This may result in
multiple output file, like tt(report.html, report01.html, report02.html) etc.
    )


