The examples in the section _struct_sheet_range use _struct_sheet_range.beg_symmetry _struct_sheet_range.end_symmetry but the dictionary only has _struct_sheet_range.symmetry _item_description.description ; Describes the symmetry operation that should be applied to the residues delimited by the beginning and ending designators in order to generate the appropriate strand in this sheet. It certainly makes sense that one can only have one symmetry operator applying at one time to a continuous run of residues so the examples should be fixed to show only _struct_sheet_range.symmetry. Frances C. Bernstein