In addition to the transaction-related records that are in the Oracle GoldenGate trail, each trail file contains a file header.

The file header is stored as a record at the beginning of a trail file preceding the data records. The information that is stored in the trail header provides enough information about the records to enable an Oracle GoldenGate process to determine whether the records are in a format that the current version of Oracle GoldenGate supports.

The trail header fields are stored as tokens, where the token format remains the same across all versions of Oracle GoldenGate. If a version of Oracle GoldenGate does not support any given token, that token is ignored. Depracated tokens are assigned a default value to preserve compatibility with previous versions of Oracle GoldenGate.

You can view the trail header with the FILEHEADER command in the Logdump utility. For more information about the tokens in the file header, see Logdump Reference for Oracle GoldenGate.