Check Routing Numbers...how read?

[kaneohe]

Are they read w/ magnetic heads (I recall reading about magnetic ink) or optical character recognition? I inadvertently wrote a long note in the memo area of check that spilled down into a space between some numbers there.
Will that interfere w/ depositing into an ATM? or worse be accepted by the ATM and get kicked out farther down the line?

I guess I could just rewrite the check but I only got 5 starter checks when opening the account and since it cost to get more, I didn't buy any.

 

[Walt34]

If it can be read by a human it will probably go through OK. If the machine can't read it via OCR the machine will kick the check out and a human will type in the numbers.

At least that's the way it used to work. It's been about ten years since I had anything to do with banking.