Allied Telesis AT-S63 - Manual (Page 448)

Chapter 28: Protected Ports VLAN Commands
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Examples
The following command uses Syntax 1 to delete untagged port 12 from the
InternetGroups VLAN:
delete vlan=InternetGroups port=12 frame=untagged
The following command accomplishes the same thing using Syntax 2:
delete vlan=InternetGroups untagged=12