difference between Set (O) and Set(M)

Hi Group ,
Really need your help in this regards.

I just confused between Set(O) and Set (M) forms. Here is my situation.

1. I am Tier 1 general visa holder completed 5 years eligible to apply ILR this month though SET(O)

2. My wife needs 2 years to apply for ILR. because she applied her first tier1 dep visa before rules 2012.

She completed here along with 3 years. But she has break of 1 year in those 3 years (She had to go india on maternity)

Now just wondered , which form would be applicable to her to apply ILR?

thanks in advance for your help

-ITZFANI

If she didn't switch to FLR(M) nor apply for an entry clearance the spouse of a settled person, then she should use SET(O).

Include evidence of subsisting marriage.