it's all down to html's id there must be only usage of any id per page our headers autocreate ids and just creates a the older html method was named anchor links eg which also must be unique per page using name like this is a hack of form submission code iirc to see clearly view source the main reason to care is if on a non wiki website you want to bookmark or link to a place that's partway down just view source and look for a id or name '' and that stuff that variable after a in the url