how is link_lang in table pligg_links and tag_links in table pligg_tags linked?

[kklol]

I'm new to pligg .
please tell me how is link_lang used in the table pligg_links.
link_lang is defined as an int in the table pligg_links
but in table pligg_tags the tag_link is defined as a varchar.

How is the int and varchar mapped?

Thanks
kk