Printable is one of the many file types/payloads supported by InterFormNG2.
Printable simply means, that the file format in the payload is one of the printable print data streams (mime-types), which means:
1.DP
2.PCL
3.PDF
4.PS
5.ZPL
The printable payloads can be generated and printed out similar to this:
The Create PCL document creates the PCL result of a merge between the input file (XML or a spooled file) and a template, and puts the result into the payload, which can then e.g. be printed like above or stored into the file system.