What i have gathered so far from this thread. The different type of application statuses: Application under review, In progress, pre-employment, employment offer.

Application under review: Indefinite waiting. You may not be in the selection pool.

In progress: Shortlisted for selection.

Pre-Employment: Passed interview and pending medical checkup.

Employment offer: Well that is obvious.

It could take up to 5 months from your interview date till you actually start work at exxon.