how to naming .so (shared object) file? is there .so file naming conventions?

[hongxing]

in directory /lib  and /usr/lib, there are many so files, each with version strings at the tail of file name .
some .so file is soft link of the others, why?

My question is:
     is there a document that describes the naming conventions of .so file ?
     or what's the rule to name .so file ?

thanks in advance?