Level 1 - Implied (ie. Nanoha, Madoka), we see the chemistry and potential parings
Level 2 - Implied Fan Service (ie. Chitose's and Chizuru), we see we see the chemistry and potential relationships but they are often put in risque situations
Level 3 - Focused but not explicitly shown (ie. Maria Watches Over Us, My HiME), we know there's relationships but we don't see any public displays of affection (at most dating and holding hands), good Level 3's you can feel the intimacy as you read/watch
Level 4 - Focused and explicitly shown (ie. Strawberry Panic!, My Z-HiME), we see relationships and…