Basicly all they are asking if it is saved under the file of PNG, instead of JPG, which is saying that you are able to fill the lines in. An example is if you get a lineart and use the 'Fill' tool, or the spilling paint can, on the inside of the lineart the whole lineart should fill with the color, not having the edges being really bad looking and they need to be able to be filled in. So basically what they are asking is if you can use the 'Fill' tool without having the edges being all messy.
~Kei

I make min e in Photoshop too and I use pencil tool(it's in the same place as brush tool). This draw pixel lines and if you save the blank image in PNG file it will be aviable to color in MS Paint.