Hi Steen;
FYI: The TX OCX object for support of the RTE Control & RT DWO is the old Sybase PB 11.x / 12.x control. This is now provided in PB2017R3 MR01 to allow easier migration to Appeon PB so that existing RTE App migration would be easier using the App's current PowerScript. This also satisfies the App requirement where a special TX feature has already been used and is not available in the TE control.
However, the default RTE & RT DW support is through the new (default) TE OCX object that was first included in PB2017 GA. The TE control is slightly different in a few areas (well documented in the PB Help) and has advantages over the TX control.
Going forward, Appeon plans to integrate the 64bit TE control into 64bit PB Apps. We cannot do this with the TX control as its only available to us in 32bit version (currently).
To answer your HyperLink question .. the RTE & RT DWO follow standard "Rich Text" mark-up. So Googling around should give you the answer (hopefully) that you are seeking.
FWIW: http://www.biblioscape.com/rtf15_spec.htm
HTH
Regards ... Chris