View Source ExTDLib.Object.ReplyMarkupForceReply (ExTDLib v0.0.4)

Instructs application to force a reply to this message.

NameTypeDescription
is_personalboolTrue, if a forced reply must automatically be shown to the current user. For outgoing messages, specify true to show the forced reply only for the mentioned users and for the target user of a reply.
input_field_placeholderstringIf non-empty, the placeholder to be shown in the input field when the reply is active; 0-64 characters.

More details on telegram's documentation.