This message allows the server to set the current free text
message content. Sending this message with a non-empty "Text"
field is equivalent to typing a new message (old contents are
discarded) in to the WSJT-X free text message field or "Tx5"
field (both are updated) and if the "Send" flag is set then
clicking the "Now" radio button for the "Tx5" field if tab one
is current or clicking the "Free msg" radio button if tab two
is current.
This message allows the server to set the current free text message content. Sending this message with a non-empty "Text" field is equivalent to typing a new message (old contents are discarded) in to the WSJT-X free text message field or "Tx5" field (both are updated) and if the "Send" flag is set then clicking the "Now" radio button for the "Tx5" field if tab one is current or clicking the "Free msg" radio button if tab two is current.
See WSJT-X source.