RECORD format field mapping (FMT):

MAP :  Fields with the same name in the from-file and to-file record formats are copied, and any fields in the to-file that do not exist in the from-file format are set to the default value specified on the DFT keyword for the data description specification (DDS) of the to-file or zero for numeric fields, blanks for character fields, current date/time for date/time fields, or null value for null-capable fields.
If *MAP is specified, *DROP can also be specified.
DROP : This value must be specified for field-level mapping if any of the field names in the from-file record format do not exist in the to-file format. If *DROP is specified, *MAP can also be specified. When *DROP is specified, all the field names that exist in both record formats must have the same attributes and relative positions in the from-file and to-file record formats, or *MAP must also be specified. Null values are copied.
NOCHK :  If the record formats of the database files are different, the copy operation continues DESPITE the differences. Record data is copied DIRECTLY (left to right) from one file to the other. FMTOPT (*NOCHK) is required when copying all record formats from a logical file with multiple formats (when RCDFMT (*ALL) is specified) to a physical file that is of the same type (source or data) as the from-file.
CVTSRC : This value is used to copy between database files, from a source file to a data file, or from a data file to a source file. It is valid only when the from-file and to-file are different TYPES (source and data).

Record format field mapping (FMT):

MAP :  Fields with the same name in the from-file and to-file record formats are copied, and any fields in the to-file that do not exist in the from-file format are set to the default value specified on the DFT keyword for the data description specification (DDS) of the to-file or zero for numeric fields, blanks for character fields, current date/time for date/time fields, or null value for null-capable fields.
If *MAP is specified, *DROP can also be specified.
DROP : This value must be specified for field-level mapping if any of the field names in the from-file record format do not exist in the to-file format. If *DROP is specified, *MAP can also be specified. When *DROP is specified, all the field names that exist in both record formats must have the same attributes and relative positions in the from-file and to-file record formats, or *MAP must also be specified. Null values are copied.
NOCHK :  If the record formats of the database files are different, the copy operation continues despite the differences. Record data is copied directly (left to right) from one file to the other. FMTOPT (*NOCHK) is required when copying all record formats from a logical file with multiple formats (when RCDFMT (*ALL) is specified) to a physical file that is of the same type (source or data) as the from-file.
CVTSRC : This value is used to copy between database files, from a source file to a data file, or from a data file to a source file. It is valid only when the from-file and to-file are different types (source and data).