Difference between -sgd- and -gd-:

[d_b_g]

I have built the boost library, but the project that I am trying to build against it is looking for: 
libboost_unit_test_framework-vc71-mt-sgd-1_33_1.lib

however, i seem to have built: 
libboost_unit_test_framework-vc71-mt-gd-1_33_1.lib

What is the difference between: 
-gd- and -sgd- ? 

Additionally, what should I do to create the -sgd- version? 

Thanks, David