Does this sentence mean word count is 900-1200 including references and appendix?
Solution 1:
It's definitely a confusing way to write it. When you use "plus", it normally means "in addition to", so they're not included in the limit, but then it's strange to include them in the sentence stating the limit.
I think what they actually meant to say is that the suggested length of the document is 3-4 pages of main text, plus references and appendix. They just worded it poorly. A limit is also not usually stated as a "suggestion".
Solution 2:
The expected word count is in addition to the notes and carefully hand crafted excuses.
The problem is eternal. "$1.95 plus tax" made me wonder; does that include the tax? Turns out it does not. That is just the limit before the excess references and artisan verbiage is added.