Dear BlackSpruce!
many thanks for your interest in this matter!
meanwhile I received an answer from Epson.
The TM-P20 supports ePOS from Epson via WLAN - not via BlueTooth unfortunatedly.
ePOS works this way:
1.) no driver or APP must be installed both on Android and on iOS
2.) The WebPage that wants to print lines must include a JavaScript file from the ePOS Library
3.) While printing the ePos JavaScript connects to a tiny WebService that resides in the Printer
4.) the ePos JavaScript sends XML (SOAP) information to the Printer.
I think this is the best solution - not the best for every printer -
but our customer will only buy the printers we recommend!
many thanks for your interest and help!
yours,
Gerald Trost