Drawing Text Symbol Location

I am looking to add custom symbols to the text editor symbols in Creo drawings.  My drawing properties symbol_font configuration is set to asme.  I know how to draw and add them to the stroked_symbol_asm.src and compile the files, but I need the location of the little thumbnail images you see in the creo ribbon (Picture attached).  I've searched through the common files to no avail.  They are probably *.pngs, but I cannot find them. 

If I were to set the symbol_font configuration to "legacy", those thumbnail images are set in loadpoint/text/resource folder.  But I want it set to asme, and again, cannot find those thumbail images ANYWHERE.  Any help would be appreciated.  Thank you.