In case of changed tab version a project will be displayed in the mapping dialog. Whether it is a hidden project or not makes no difference.

The change "hidden"/"visible" does not take place in the table (tab file), but in the project (prj file).

So if the hiding is the only change, the project will not occur in the mapping dialog. In the reverse case like change from "hidden" to "visible" the project will not occur in the mapping dialog as well.

However, if changes have been made on hidden projects they have to be mapped. Then they will occur in the mapping dialog quite normally as all others, too. For example, it could be wanted to hide the actual projects and then to link to these projects. In such a case it will be visible, just via link. Then linked projects could receive ERP numbers again.