The IRS has issued an internal Memorandum on its ruling position on Opinion Letter applications on Spousal Provisions in Section 403(b) Plans.

Document Excerpt
This sets forth Interim Guidance on the processing of IRC § 403(b) pre-approved plan applications for opinion and advisory letters with respect to spousal benefit provisions. This is not a pronouncement of law and is not subject to use, citation, or reliance as such. Nothing in this interim guidance shall affect the operation of any other provision of the IRC, regulations, or guidance thereunder.

Link
https://www.irs.gov/pub/foia/ig/spder/TEGE-07-0316-0006.pdf