When i saw this Lock Symbol in vROPS 6.0 Tags, then i was wondered what does this means? I haven't found an actual explanation for the lock symbol, but I'm fairly certain it is just to indicate the Pre-defined object tags
Predefined Object Tags
vRealize Operations Manager includes several predefined object tags. It creates values for most of these tags and assigns objects to the values.
For example, when you add an object, vRealize Operations Manager assigns it to the tag value for the collector it uses and the kind of object that it is. It creates tag values if they do not already exist.
If a predefined tag has no values, there is no object of that tag type. For example, if no applications are defined in your vRealize Operations Managerinstance, the applications tag has no tag values.
Each tag value appears with the number of objects that have that tag. Tag values that have no objects appear with the value zero. You cannot delete the predefined tags or tag values that vRealize Operations Manager creates.
Tag values are License Groups found under are assigned to the license groups during vRealize Operations Manager installation. See Add a vRealize Operations Manager License Group.