MS_FONTPATH vs. MS_TTFPATH

According to USTN Content,

MS_FONTPATH "specifies a list of directories that are searched to locate fonts.  Any .RSC, .SHX, or .TTF/ttc file found in any directory in the list is loaded and/or available for use."

According to this Bentley Communities topic,

MS_TTFPATH "specifies the path to the directory which contains the True Type fonts."

These sound identical where true type fonts are concerned, so I defined both of them for my project.

My question is this: Why, with both of these variables defined, do the .ttf files in the support/fonts directory still show up in red?!