Thanks! That certainly cleared things up for me.
I think my initial confusion started when my wife and I ate at the 100 Candles at Ivans. This was the ONLY time during that trip that I used a credit card, strictly because the bill was well over $100 and also because I trusted the staff at Catcha. When I got the credit card slip back to sign, I noticed that there was no spot to add a tip. I did see that the Service Charge was added in but there no placed for me to add a tip on credit card (I didn't have enough cash on me for a tip either). When I asked the server if I could give a tip on my credit card she seemed a little surprised and said that they would have to run the tip through on a separate transaction. No big deal for me - I just had to sign 2 slips. However, I thought the reason there was no space on the CC slip to add a tip was because the restaurant considered the Service Charge to be the tip.