rspo/archive_format is a SAP Parameter attribute which is used to control Format for output data for the ArchiveLink archiver information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Selection of the format in which archiving requests are written through
the spool work process.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.