Subsequently, the molecules are processed by the ChEMBL Structure Curation Pipeline Checker to verify the validity of the chemical structures and identify any serious problems like valence errors. Molecules flagged with Checker error codes six or higher are marked as failed entries and filtered at this stage (if necessary, these failed entries can be manually reviewed, corrected, and resubmitted). Those that successfully pass the Checker are advanced to the next processing step. COCONUT identifiers ("CNP" prefix and 7 digits) issued previously are mapped and preserved to resolve to the same molecular entity from COCONUT 1.0, and new identifiers are issued to new entries. Stereochemical variants of the same molecule are grouped under the same identifier and are issued a unique postfix to the COCONUT identifier.