I just want to jump in for my favorite, "^".

It seems to be rarely used. If you have a "comment" field for humans to use almost all of the other punctuation on the keyboard will be used by somebody.

• Tom's junk.
• 13 @ $4.32 each
• primary john; secondary phil;
• upstairs (behind the door)

But rarely 'tell mark ^ paul'. Plus it hangs high in the line and has space below for visual hooking.