The Maintopmodule block: I can't edit its name

Hi.
I'm using J 3.4.3 and TC 3.4.1.
When I create a new template, I select the Model 14 one.
To maintain the compatibility with VirtueMart 3, I try to change the name of the maintopmodule block to maintop, but an error message appears saying the name is already used.
I cant't figure out where this name is used.
Note that the position of the module is actually maintop, but it should not create problems; should it? I changed the name of the position, but the name of the block can't be maintop anyway.
Has anyone the same problem?

Hi
the ID "maintop" is used into the Template Creator interface. You can not use it for a module block
But if you disable the maintop using the layout icon on "maincontent", then you will not have any "maintop" block in the rendered template.
I don't know why you need this ID, but you can still use the module position "maintop" if this is what you need
CEd