Java - Offline IDOC creation - library?

[idoccreation]

Hi,

I need to generate IDOC files offline - ie on a system not connected to SAP. It appears the SAP IDOC /JCo libraries require that the system is connected to SAP and will support the transfer of an IDOC to SAP but do not support the simple creation of an IDOC text file.

Is there another library that supports this task, or, if not, is there a layout description of an IDOC file and the constituent fields available here (or elsewhere)?

thanks in advance for any guidance