Using Joomla 1.5.22 & JoomSef 3.8.1

What are the metacustoms that appear on the phpMyAdmin under SEFurls? I've got a:0:{} under this column for some and not for others - does this mean anything?

I've got a feeling it has something to do with the com_content variables - I think I read somewhere that an upgrade to Artio (can't remember to which version), would automatically have normal variables added but not sure. My com_content doesn't have any variables listed under it (from joomla backend I mean) so could be hiding somewhere. I know I used to have the following:
+^[0-9]*$=limit,limitstart,month,showall,year
+^[a-zA-Z]+$=task,type,view
+^[0-9]+(:[a-zA-Z0-9._-]+)?$=catid,id,sectionid

Is it still necessary to insert them or not?

Thanks.