It is referring to the letters of the alphabet. When you write in cursive, you have to dot the letter i and cross the letter t after you have written the entire word. It is easy to forget these details if you are in a hurry, and that's what this idiom means: Pay attention to details.
That's dope!!!
As you're saying, dot the letter i, which means you should remember to put the dot ( . ) above the I, it should be i. And cross the letter t, which means to put the short line ( - ) across the L, it should be t, according to your explanation, because we're always easy to forget these details if we're in a hurry, so that's what this idion means, Pay attention to small details.
right?
thanks,mykwyner.:lol::lol::lol: