See Boost getting started windows section 6.3 naming and section 6.1 on Unix naming
The ones that deal with -mt and d are
-mt Threading tag: indicates that the library was built with multithreading support enabled. Libraries built without multithreading support can be identified by the absence of `-mt`.
-d ABI tag: encodes details that affect the library's interoperability with other compiled code. For each such feature, a single letter is added to the tag as listed in this table:
Key Use this library when (Boost.Build option)
s linking statically to the C++ standard library
and compiler runtime support libraries.
(runtime-link=static)
g using debug versions of the standard and runtime support libraries.
(runtime-debugging=on)
y using a special debug build of Python.
(python-debugging=on)
d building a debug version of your code.
(variant=debug)
p using the STLPort standard library rather than
the default one supplied with your compiler.
(stdlib=stlport)