(Aka second order draft)
The IPCC review process's second-order draft, which is a review of the first order drafts that is performed by scientific experts.
Example Usages -
1. "The main stages of the IPCC review process are the review of the “first-order draft” (FOD) by scientific experts, the review of the “second-order draft” (SOD) by experts and governments and the government review of the final draft of the summary for policymakers. Following this, the final draft report and its summary for policymakers are submitted for acceptance and approval to the IPCC Plenary."
(Source: Review of Working Group contributions to the IPCC Fifth Assessment Report (AR5) )