DCL:GRPH1:SWPACK: Machine-Dependent Routines:Varioous Databases
When filling polygons with solid colors (using tone pattern index with 999 as  
the last 3 digits), the color index is converted into pattern index for dot  
patterns using this conversion table when the output device cannot handle color  
(or when the internal variable 'LCL2TN' handled by  SGpGET/SGpSET  
is set to   
.TRUE.  ) This must be present as a file indicated by the internal  
variable  'CL2TN'. 
This data file is not directly used in SWPACK. Instead, it is accessed by SZCLTN in SZPACK. The file name is searched by SWQFNM. This data is read when the tone primitive is first called, and is not accessed after that.