pub fn classify_ack_rej(text: &str) -> Option<(bool, &str)>Expand description
Classify a message text as an APRS ack or rej control frame.
Per APRS 1.0.1 §14, ack and rej frames have text of the exact form
ack<id> or rej<id> where <id> is 1-5 alphanumeric characters and
nothing follows. This helper avoids the false-positive that naive
starts_with("ack") matching would produce for legitimate messages
that happen to begin with those letters (e.g. “acknowledge receipt”).
Returns Some((is_ack, message_id)) for control frames, None
otherwise. is_ack is true for ack, false for rej.