Neglecting extern variable in ASAP file

Hello,

I'm using Embedded Coder (ert) for code generation with an ASAP2 interface which generates an a2l file. Let's say I have an variable "input" used to communicate with other modules. "input" is defined as Simulink.Signal and its storage class is set to ImportedExtern, since it's an extern variable. The variable "input" also appears in the a2l file, which leads to an error while compiling the whole software.

Now the question: how can I tell the code generator to neglect the variable "input" in the a2l file? Setting the storage class of "input" to "Auto" is no option, since it's not extern anymore.

Thanks.