how to use OPT ALT in Boeing 777

[sm165019117]

OPT ALT is determined based on aircraft gross weight and cruise speed in still air. I am confused why BOEING put this in CRZ page, we determine the CRZ alt by using the MAX(-1000ft) or REC alt (within forecast and temperatures)
how to use OPT ALT during operation or be compared with something or to prove something?
new beginning at B777~

[Check Airman]

I imagine it’s just there as a reference. I try to fly at the REC altitude.

[MarkerInbound]

Older FMCs didn’t have REC, just MAX and OPT. If another airplane is at you recommend altitude OPT can tell you to ask for the next level above or below REC.

[deltahotel]

767 B12. So for simple me, OPT is where the wing is working best, REC overlays that with input winds.

OPT – displays the most economical altitude based on airplane gross weight.

MAX – displays the maximum cruise altitude based on:

• engine out operation

• selected speed option

• without any altitude or speed constraints, and

• capable of a 100 feet per minute climb rate.

RECMD – displays the most economical altitude based on airplane performance and winds.

[awair]

Use to climb 100’ at a time when cleared for a block (eg Australia).

This is effectively a Cruise climb. For 100’, aircraft remains in VNAV PTH. No substantial power change.