In that case, the layer will be created empty. You should be careful, however, about putting plug-ins into layers, as they can sometimes fail to function properly. It guarantees that the layer is the size and shape you want it to be. Otherwise, the document runs right up to the edges of the layer. You cannot have margins without having a fixed bottom.
CLIP specifies a clipping rectangle for the layer that contains it.
The clipping rectangle will normally overlap with the layer itself. Only the part of the layer which is within the clipping rectangle will be visible. Hence, this layer will be 50 pixels down from the top and 75 pixels in from the left of the screen, and will be 200 pixels wide. The CLIP parameter specifies a clipping rectangle using 4 numbers that specify, respectively, the left, top, right, and bottom of the rectangle. The first two numbers, TOP and LEFT, specify the location of the top left corner of the clipping rectangle.