[chirp_devel] Adding FT-7100: Tone Mode 'CTCSS Bell' is not in valid list

[Bruno]

Hello

My name is Bruno Maire, HB9GHC and I would like to add the Yaesu FT-7100.

Chirp read from radio works over the serial port.
Chirp read from and write to "FT-7100 Programmer" from "RT Systems" works over 
the serial port.

I am struggling with tone modes:
TONE_MODES = ["", "Tone", "TSQL", "CTCSS Bell", "DTCS"]
However "CTCSS Bell" is not known to chirp.
There is an impact on other radios if I try to have it accepted with:
mem._valid_map["tmode"] = TONE_MODES

What is the correct procedure to have "CTCSS Bell" as valid tone mode?

Best regards,
Bruno