Good question. The answer in part may be found here:
Instrument Procedures Handbook (IPH)
(Chapter 5 refers)
The navigation equipment that is required to join and fly
an instrument approach procedure is indicated by the title
of the procedure and notes on the chart. Straight-in IAPs
are identified by the navigation system by providing the
final approach guidance and the runway with which the
approach is aligned (for example, VOR RWY 13).
Circling-only approaches are identified by the navigation
system by providing final approach guidance and a letter
(for example, VOR A). More than one navigation system
separated by a slant indicates that more than one type of
equipment must be used to execute the final approach (for
example, VOR/DME RWY 31). More than one navigation
system separated by the word “or” indicates either
type of equipment can be used to execute the final
approach (for example,VOR or GPS RWY 15).
In some cases, other types of navigation systems, including
radar, are required to execute other portions of the
approach or to navigate to the IAF (for example, an NDB
procedure turn to an ILS, or an NDB in the missed
approach, or radar required to join the procedure or identify
a fix). When ATC radar or other equipment is required
for procedure entry from the en route environment, a note
is charted in the planview of the approach procedure chart
(for example, RADAR REQUIRED or ADF
REQUIRED). When radar or other equipment is required
on portions of the procedure outside the final approach
segment, including the missed approach, a note is charted
in the notes box of the pilot briefing portion of the
approach chart (for example, RADAR REQUIRED or
DME REQUIRED). Notes are not charted when VOR is
required outside the final approach segment.
Pilots should
ensure that the aircraft is equipped with the required
NAVAIDs to execute the approach, including the missed
approach.
I assume Europe have a similar document.