Not quite. The secession conventions issued various documents. The Ordinances of Secession were straightforward, and usually simply stated that the Union was dissolved, with the listing of delegates voting in favor, and those not in favor. The statements known as Declaration of Causes were also official documents released by the conventions. These were supporting documents that laid out the rationale for leaving.
In the case of Mississippi, their convention was held between Jan. 7th and Jan. 26th, 1861. I have quoted their words. You cannot hide from nor obfuscate these facts.
https://web.archive.org/web/19980128034930/http://sunsite.utk.edu/civil-war/reasons.html