>>? GOMONTH(DATE()-22,-6-18*12)
>>
>>Cetin
>
>* CHECK with the correct definition Age = (((Birth+Y)+M)+D)
> ? GOMONTH(GOMONTH({^1988/2/29},.Years*12),.Months)+.Days
> * CHECK with a bad definition
> ? GOMONTH({^1988/2/29},.Years*12+.Months) + .Days
> ? gomonth(GOMONTH({^2006/09/21} - .Days, - .Months), - .Years *12)
> ? GOMONTH(DATE()- .Days,-.Months-.Years*12)

Why don't you check your correct definition:
? GOMONTH({^1988/2/29},18*12+6)+22
? GOMONTH(GOMONTH({^1988/2/29},18*12),6)+22
Why are they different?
For another sample explain this:

? Gomonth(GOMONTH(GOMONTH({^1988/2/29},13),-1),1)

I see that you want to play gomonth() tricks on me:) One you claimed to be a bad definition has the answer already, no?
Cetin