Real Options Pa and Pe values

Please tell me whether my understanding is correct regarding Pa and Pe

1-Abandon(Put option) option Pa is the value which will be lost by selling the project earlier and Pe is the value we received by selling.

2-Delay option(Call option)
Pa is the p.v of the project
Pe is the capital expenditure that can delayed.

3-Expansion option.
Pe is the amount of cost needed for expansion. It
but what is the Pa in expansion? and expansion is like call option?

Please mention any error i made in 1 and 2 and explain 3.