It is not.I understood that 'Nashville number system' expressly refers to using Arabic numerals and not Roman numerals to designate the chords - is it different for pedal steel?
Roman Numerals are used in standard music theory, Arabic Numerals are used in the Nashville Number System. This has always kinda bugged me about Jesse's otherwise superlative set of charts, mainly because I am mildly dyslexic and cannot "read" roman numerals without having to stop and carefully think about the differences between IV and VI, whether there are 2 or 3 "I" symbols, etc.
This means that whenever I look at these charts and try to discern patterns, my mind "blocks" me from doing so because of my difficulty with interpreting the roman numerals.
So with that in mind, and with all respect to Jesse, I have edited his charts to use Arabic Numerals instead.
You can find this NNS-Interpreted PDF HERE
(Jesse, if you would like to host this NNS-Interpreted PDF on your site instead (or if you would prefer this edited version to not be available at all), just let me know and I will remove my link. I make no claim of authorship in any way on this edited version.)