[Therion] How to include Metapost code from outside files

[Bill Gee]

Hello everyone -

I have quite a bit of Metapost code for custom symbols.  Rather than repeat 
several hundred lines in every layout/endlayout pair, I would like to put the 
code in its own file and then <include> that file in the thconfig file.  How is 
that done?

I tried using both "input sourcefile" and "source sourcefile".  The same error 
comes up for both.  Text below.

According to the Therion Book, the only valid place for code/endcode pairs is 
inside a layout/endlayout pair.  Is that true?

Thanks - Bill Gee

=============
therion 5.3.13
initialization file: /usr/local/etc/therion.ini
reading ... done
configuration file: thconfig
reading ...
therion: error -- thconfig [14] -- thconfig [14] -- unknown option -- input 
CustomSymbolsCode.txt
writing xtherion file ... done



therion 5.3.13
initialization file: /usr/local/etc/therion.ini
reading ... done
configuration file: thconfig
reading ...
therion: error -- thconfig [14] -- thconfig [14] -- unknown option -- source 
CustomSymbolsCode.txt
writing xtherion file ... done