A "control list" is not a "UN mandated gun registration system." Here is a link to a Commerce Department site re: export controls. There is a link to a "control list" on the page. A "control list" is basically a list of (a) specific items covered by certain import/export provisions and/or (b) criteria for determining whether items are covered by said import/export provisions.
In this context, Article 2 lists 8 categories of "conventional arms" covered by the treaty. The "control list" would be a document that defined what types of arms fall into each of the categories. It's not a gun registry.
You need to read all the parts of the treaty. They work together. The documents always tend to be self referencing, so parts scattered all over will affect other parts.
Thus Article 2
4. Each State Party shall establish or update, as appropriate, and maintain a national control list that shall include the items that fall within Paragraph 1 above, as defined on a national basis, based on relevant UN instruments at a minimum. Each State Party shall publish its control list to the extent permitted by national law.
Article 6
3. Each State Party shall take all appropriate legislative and administrative measures necessary to implement the provisions of this Treaty and designate competent national authorities in order to have an effective, transparent and predictable national control system regulating the transfer of conventional arms;
4. Each State Party shall establish one or more national contact points to exchange information on matters related to the implementation of this Treaty. A State Party shall notify the Implementation Support Unit (See Article 13) of its national contact point(s) and keep the information updated.
Article 11
1. Each State Party shall maintain records in accordance with its national laws and regardless of the items referred to in Article 2, Paragraph A, with regards to conventional arms authorization or exports, and where feasible of those items transferred to their territory as the final destination, or that are authorized to transit or transship their territory, respectively.
2 Each State Party shall maintain records in accordance with its national laws and regardless of the items referred to in Article 2, Paragraph A, with regards to conventional arms authorization or exports, and where feasible of those items transferred to their territory as the final destination, or that are authorized to transit or transship their territory, respectively.
So basically any arm which is imported has to be tracked for 10 years (registered) and this tracking must be reported to the local UN bureaucracy.