In the PDB format document there is a new record type specified that has not yet been implemented. It would seem useful to have an equivalent in an mmCIF but I could not find any in the dictionary. Here are the relevant parts of the PDB decsription: CAVEAT warns of severe errors in an entry. Use caution when working with this entry. COLUMNS DATA TYPE FIELD DEFINITION 1 - 6 Record name "CAVEAT" 9 - 10 Continuation continuation Allows concatenation of multiple records 12 - 15 IDcode idCode PDB ID code of this entry 20 - 70 String comment Free text giving the reason for the CAVEAT PDB will add this record to incorrect entries that are not withdrawn from the set of released entries. This record will be used sparingly, and only after an external review has been made. CAVEAT will be added by the PDB to entries known to be incorrect. Example: 1 2 3 4 5 6 7 1234567890123456789012345678901234567890123456789012345678901234567890 CAVEAT 1ABC THE CRYSTAL TRANSFORMATION IS IN ERROR BUT IS CAVEAT 2 1ABC UNCORRECTABLE AT THIS TIME Frances C. Bernstein