It looks like you’re referring to the for version 1.6.1170 (often colloquially referred to or mistyped as 1147 in modding circles following recent updates).
In modding slang, “top” refers to the highest stable release for a given patch level. For 1.1.47, SKSE 1.6.16 is the “top” because: skse for skyrim 1147 top