[libvirt] Exact meaning of "nativeMode" attribute in vlan tags

You'd think that I would know this, since I'm the person who reviewed jrobson's patch adding support for the nativeMode attribute to the vlan tag element. But you'd be wrong. Here is what the config looks like: <vlan trunk='yes'> <tag id='42' nativeMode='untagged'/> <tag id='47'/> </vlan> I understand that trunk='yes' means that packets with any of the tags listed in a <tag> subelement can be sent out this port (and the tag will *not* be removed), and likewise packets arriving into the bridge from the port are allowed to have any of the listed tags (and, again, no tag will be removed). But what exactly do nativeMode='untagged' and nativeMode='tagged' mean? As I understand it, (nativeMode='untagged'|nativeMode='tagged') means that packets (arriving from|sent to) the port (without a tag/with that tag) will be (tagged|untagged). Can someone who fully understands this please select A or B for each of the 4 parenthesized items (in as many permutations as make sense). I guess that in one of the modes, untagged packets going in one direction or the other will be tagged, and vice versa, I just don't know which direction does which, and for which mode, and don't want to guess. (I'm asking this because I want to implement identical functionality for standard Linux host bridges - I want to make sure there are no surprises for people switching between OVS and Linux host bridge implementations).