From "International Consensus Recommendations for the Treatment of Pediatric NMDAR Antibody Encephalitis":
A steering committee (R.C.D., M.L., T.T., M.N., and M.E.) carefully selected a panel of 27 experts with representation from all continents (later referred to as “the Panel”), and based on the individual: (1) being a specialist (usually pediatric neurologist or rheumatologist) with clinical and/or research expertise in pediatric NMDARE; these experts were identified as lead clinical researchers in the field based on the systematic review conducted before the consensus recommendations project (paper in preparation), or were nominated by national child neurology societies;
What is the meaning of the phrase in bold? Each candidate was obligated to write a systematic review about the topic in order to be identified as a lead researcher? Then why it's "paper in preparation" and not "papers in preparation"?
Or maybe the steering committee wrote a systematic review about the selection of candidate experts? But this is odd.
I hope this question is on-topic, since it's related to the process of preparing a medicinal guideline. If it's not on-topic, feel free to move to a different StackExchange section.