If a business doesn't have Arisia registered as a non-profit, you'll need to give them copies of both forms to avoid paying sales tax.
Links:
[1] http://corp.arisia.org/articles
[2] http://corp.arisia.org/sites/corp.arisia.org/files/articles.pdf
[3] http://corp.arisia.org/sites/corp.arisia.org/files/articles.pdb
[4] http://corp.arisia.org/bylaws
[5] http://corp.arisia.org/sites/corp.arisia.org/files/ArisiaBylaws.Google.pdf
[6] http://corp.arisia.org/policies
[7] http://corp.arisia.org/sites/corp.arisia.org/files/ArisiaPolicies.Google.pdf
[8] http://corp.arisia.org/
[9] http://corp.arisia.org/sites/corp.arisia.org/files/expense.html
[10] http://corp.arisia.org/sites/corp.arisia.org/files/expense.pdf
[11] http://corp.arisia.org/sites/corp.arisia.org/files//expense.rtf
[12] http://corp.arisia.org/sites/corp.arisia.org/files/income.html
[13] http://corp.arisia.org/sites/corp.arisia.org/files/income.pdf
[14] http://corp.arisia.org/sites/corp.arisia.org/files/income.rtf
[15] http://corp.arisia.org/grant-form
[16] http://corp.arisia.org/grant-budget