From the draft negotiating text on dispute settlement (Word doc), released last Thursday by the WTO, here's the section on remand:
17.12(b) Where the Appellate Body finds that there is not a sufficient factual basis to complete the analysis with respect to certain issues, it shall in its report provide a detailed description of the [types of] findings that are required to complete the analysis with respect to those issues.
With more details here:
1. Where the Appellate Body has identified certain issues according to paragraph 12(b) of Article 17, [a complaining party] [the party who advanced the particular claim or defence to which the unresolved issue relates] may refer [such] [that] issue[s] to the panel.
2. The referring party shall make the referral before the adoption of the Appellate Body report. It shall do so in writing and shall identify the specific issues it seeks to have addressed by the panel as well as the relevant paragraphs in the Appellate Body report. The referring party shall address the referral to the panel and shall notify the DSB thereof.
3. The panel may examine only those issues with respect to which the Appellate Body has expressly found that there is not a sufficient factual basis to complete the analysis, and that [a party to the dispute][the referring party] has identified in accordance with paragraph 2.
4. The panel shall make such findings and recommendations, in accordance with the [guidance][description] provided by the Appellate Body pursuant to paragraph 12 of Article 17, as will assist the DSB in making its rulings and recommendations.
5. As a general rule, the panel shall circulate its report within 90 days after the date of referral of the matter to it. When the Panel considers that it cannot provide its report within 90 days, it shall inform the DSB in writing of the reasons for the delay together with an estimate of the period within which it will provide its report.
6. If a party appeals the report of the panel, Article 17 and Article 17bis apply to Appellate Body proceedings and the adoption of the Appellate Body report.]
In the original text, there are shaded parts that reflect proposed changes by the Chairman, but it was too much of a hassle to reproduce them in this post, so see the original for the full details.