Hide layer from parameter like in 'Track matte key' effect

Hi,

I am developing a video effect plugin for Premiere (but with AE SDK, so I decided to write it in this forum).

I would like to have a functionality similar to 'Track matte key' effect which is shipped with application.

Specifically, I want the layer, which is selected as a parameter, to be not visible directly. Now in my plugin I can access that layer's data, but it is still visible and covers my composition.

I haven't found anything like that in documentation, examples or other questions here.

Anyone knows how to do it?

Edit:

There is a param flag PF_ParamFlag_LAYER_PARAM_IS_TRACKMATTE, but its only effect is that after checkout I get empty buffer. Is this flag related to my first question and how to use it correctly?