IBM i Source Physical Files Support

Source physical files have a common, known DDS. This DDS specifies the following record format:

• First six bytes contain a sequence number
• Next six bytes contain a line modification date
• Remaining number of bytes are text data This length can be between 1 and 32754 bytes for single-byte character systems.

USESRCSEQ Attribute

A single attribute, USESRCSEQ (with values of YES or NO) governs whether or not the sequence number and modification date are included in the source record when transferring a source physical file. How this happens depends on the mode type of the transfer. By default, this value is set to NO, meaning sequence numbers and modification dates are to be stripped.

When writing a source physical file, the USESRCSEQ attribute specifies whether or not source sequence information is expected to be included in the source data. If the value is set to NO, UDM generates sequence number and modification date information. Otherwise, the first 12 bytes of each source record contain that information. This value is sent as a source attribute in IBM i to IBM i copies, so unless it is overridden, it automatically will tell the destination side if the sequence numbers are in the data. Allowing this option to be set permits the effective copying of source physical files from non-400 systems that already contain sequence number information.

Additional Attributes

When creating UDM sequence data, two additional destination side attributes are used.

• SEQSTART specifies the starting sequence number of the first record written and range from 0000.01 to 9999.99. The default is 0001.00.
• SEQINCR indicates how much the sequence number is incremented from record to record. Valid values are 00.01 to 99.99. The default value is 01.00.

SEQSTART and SEQINCR are sent as source attributes, but used on the destination side only when a new file is being created. If UDM is replacing or appending to an existing source physical file, the values of SEQSTART and SEQINCR of the existing destination file are used.