When/How to use right name in hidden form elements

Hi!
Some time ago i fount small hint in oxid code about meaning names of hidden html form elements:
‘cnid’, // category id
’mnid’, // manufacturer id
’anid’, // active article id
’tpl’, // spec. template
’listtype’, // list type
’searchcnid’, // search category
’searchvendor’, // search vendor
’searchmanufacturer’, // search manufacturer
// @deprecated since v5.3 (2016-06-17); Listmania will be moved to an own module.
‘searchrecomm’, // search recomendation
’recommid’ // recomm. list id

  • And now what is the differences beetwen using aid and anid when i want make some request. In mostly cases this is the same value.
  • How can i get it when/which key is required in form, for example when i work with products list view?