Please help for AFL coding in Ambibroker

To initiate a Buy signal:

1 .The TD REI must be below -40 for six or fewer periods.
2. There must be a lower close than the close of the prior price bar.
3. The open of the next price bar must be less than ,or equal to ,the two prior price highs; and
4. The market must trade above the open and post a high above either one of the prior two price highs.

To Trigger a sell signal:

1 .The TD REI must be above +40 for six fewer periods.
2. There must be a higher close than the close of the prior price bar.
3. The open of the next price bar must be greater than ,or equal to ,the two prior price low; and
4. The market must trade below the open and post a low below either one of the prior two price lows.

what is this?

like this,

Weakness: TD ReI stays above +40 (or +45) for fewer than six price bars, and then falls back = Expect near-term gains.

Strength: TD ReI stays below -40 (or -45) for fewer than six price bars, and then recovers =
Expect short-term recovery.

I believe he's asking, what is a 'TD REI'? Because I don't know what it is either.

TDREI = Tom DeMark Range Expansion Index