Second afterthought and this puzzle's theme

• Letter adjunct: Abbr.
• Correspondent's "Oh, and another thing ..."
• Second afterthought on a ltr
• Thought after an afterthought: Abbr
• Ltr.'s second add-on
• "Oh, and another thing," on a ltr
• Leter ended, for short
• Second addition to a ltr
• Letter apps.

Wikipedia Word definitions in Wikipedia
PPS may refer to: