i18n module developer documentation

I'm updating a contrib module to be i18n-compatible, and am finding the documentation thin on the ground, mostly a few notes here: http://drupal.org/node/313262

Digging through the code it appears that aside from node content, the main i18n support is for drupal variables. So, for a module to be compatible we need to make sure that it stores its data in drupal variables. Is this correct? The module I'm working with uses a custom table instead so I figure that switching to drupal variables is probably the best way to add i18n support.