18.3  UNIT_NUMBERS 

The following logical unit numbers are used:
     Unit Routine   Usage
     1    T2SETH    Histogram input
     6    All       Error message/Information output
     7    TDMAIN    Journal file output
     8    All       Listing output
     9-19 TDMAIN    Input
     86   All       Error message for deferred errors
The  journal  file,  and  listing  are not output unless the following set
commands are used:
     TD:SET FILE LOG filename
     TD:SET FILE LIST filename