specify area without solder mask

Hi, I'd like to know how I can specify an area that doesn't have a solder mask? in other words how can I specify (in the gerbil file or something) the area not to have a solder mask for the company that is producing the prototype?
Thank you for your inquiry.

In Quadcept, the "Solder" layer is defined as a layer for solder resist opening, and objects drawn on this layer becomes an area without solder mask.

[Layer(Default Layer)]

Therefore, if there is some object in this layer, the area of the object will not have a solder mask, and if there is no objects on the layer, a board will be coated with resist when manufacturing the board.

Thank you.

So in other words there isn't a way to create a plane that tells the manufacturer not to put solder mask. I'm attaching an image to show what I'm after
I am sorry I did not make it clear enough.

You can tell the board manufacturer not to put solder mask by placing an object on the "Solder" layer. The layer is for removing a solder resist from a board. For example, if you draw the following figure on that layer, you can specify the area without solder mask like the image you attached.

* The object is created with the Filled Polygon command.
[Drawing Filled Polygons]

If you have anything unclear, please let me know.

Thank you.