kotoba:: // The package name
auth. // The language file name
register // The phrase or word that you want to call
account :: standard account terminology
auth :: terminology that is more specific towards authorization and authentification
button :: various terminology appearing on buttons
cms :: typical terminology used by CMS's
email :: email template phrases and words
general :: bases phrases and words
group :: group terminology
permission :: permission terminology
role :: role terminology
table :: various terminology appearing on table column headings
Note: Sometimes you have words or phrases that can fall into both the button, table and general categories.
I separated these since you might want to have them slightly different, like capitalizations or similar.