Interpretation of /lnsig2u of xtprobit model

[ghimire]

Hello,
I have a problem to read/interpret the stata outcome obtained from the xtprobit model. I am wondering if anyone has some idea to interpret the  /lnsig2u  shown up in stata outcome after the xtprobit command.
 
With best regards,
Ramesh Ghimire
Agricultural and Applied Economics
305 Conner Hall, The University of Georgia
Athens, 30602, GA
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[ramesh]

Hello,
I am using xtlogit model, which is in the form of: y= b0+b1.x1+b2.x1*x1+b3.x3 +b4.x4). I have one squared term (x1*x1) and two of my independent variables (x3 and x4) are binary and after using the 'xtlogit y x1 c.x1#c.x1 x3 x3' followed by 'margins, dydx(*) atmeans' I got the same beta coefficient as marginal effect, which is not correct. Is there any idea to correctly specify the marginal effect?

Regards,
Ramesh