setAllowedContentTypes: how to use it on more than one filetype

Question

In NSOpenPanel this is the easy part, enabling 1 filetype for opening:

NSArray uttypes;

uttypes=[UTType typesWithTag:@"ach" tagClass:UTTagClassFilenameExtension conformingToType:nil];

[openfilepanel setAllowedContentTypes:uttypes];

Now what do I do if I would like to enable more than one filetype for opening? I only want to be able to open files that 'belong to' my application, no others.

working on MacOS 12.2

Michel